From 19381696788b6f460c3997ab989a8b76636683a9 Mon Sep 17 00:00:00 2001
From: fredlacs <32464905+fredlacs@users.noreply.github.com>
Date: Sun, 1 May 2022 15:15:10 +0100
Subject: [PATCH 1/5] Add initial support for custom errors

---
 contracts/v0.8.9/CustomError.sol              |  26 ++++
 .../test/CustomError.test.ts                  |  48 +++++++
 packages/target-ethers-v5-test/test/common.ts |   2 +-
 .../v0.8.9/CustomError/TestToken__factory.ts  |  60 +++++++++
 .../factories/v0.8.9/CustomError/index.ts     |   4 +
 .../factories/v0.8.9/CustomError__factory.ts  |  65 +++++++++
 .../types/factories/v0.8.9/index.ts           |   1 +
 packages/target-ethers-v5-test/types/index.ts |   2 +
 .../types/v0.6.4/DataTypesInput.ts            |   2 +
 .../types/v0.6.4/DataTypesPure.ts             |   2 +
 .../types/v0.6.4/DataTypesView.ts             |   2 +
 .../types/v0.6.4/Events.ts                    |   2 +
 .../types/v0.6.4/Issue428_Reproduction/A.ts   |   2 +
 .../types/v0.6.4/Issue428_Reproduction/B.ts   |   2 +
 .../types/v0.6.4/Library/Lib.ts               |   2 +
 .../types/v0.6.4/LibraryConsumer.ts           |   2 +
 .../v0.6.4/Name-Mangling/NAME12mangling.ts    |   2 +
 .../types/v0.6.4/Overloads.ts                 |   2 +
 .../types/v0.6.4/Payable/Payable.ts           |   2 +
 .../types/v0.6.4/Payable/PayableFactory.ts    |   2 +
 .../types/v0.8.9/CustomError.ts               | 123 ++++++++++++++++++
 .../types/v0.8.9/ISimpleToken.ts              |   2 +
 .../types/v0.8.9/Issue552_Reproduction.ts     |   2 +
 .../v0.8.9/KingOfTheHill/KingOfTheHill.ts     |  12 ++
 .../v0.8.9/KingOfTheHill/Withdrawable.ts      |   2 +
 .../types/v0.8.9/Rarity/ERC721.ts             |   2 +
 .../types/v0.8.9/Rarity/ERC721Enumerable.ts   |   2 +
 .../types/v0.8.9/Rarity/IERC721.ts            |   2 +
 .../types/v0.8.9/Rarity/IERC721Enumerable.ts  |   2 +
 .../types/v0.8.9/Rarity/IERC721Receiver.ts    |   2 +
 .../types/v0.8.9/Rarity/Rarity.ts             |   2 +
 .../types/v0.8.9/SimpleToken.ts               |   2 +
 .../types/v0.8.9/index.ts                     |   1 +
 .../types/v0.8.9/nested/a/NestedLibrary.ts    |   2 +
 .../types/v0.8.9/nested/b/NestedLibrary.ts    |   2 +
 .../target-ethers-v5/src/codegen/errors.ts    |  64 +++++++++
 .../target-ethers-v5/src/codegen/index.ts     |  21 ++-
 .../types/v0.8.9/CustomError.ts               |  40 ++++++
 .../types/v0.8.9/CustomError/TestToken.ts     |  40 ++++++
 .../types/v0.8.9/CustomError/index.ts         |   4 +
 .../target-web3-v1-test/types/v0.8.9/index.ts |   1 +
 packages/typechain/src/parser/abiParser.ts    |  27 ++++
 packages/typechain/src/utils/signatures.ts    |   4 +-
 .../typechain/test/parser/abiParser.test.ts   |  33 +++++
 44 files changed, 621 insertions(+), 5 deletions(-)
 create mode 100644 contracts/v0.8.9/CustomError.sol
 create mode 100644 packages/target-ethers-v5-test/test/CustomError.test.ts
 create mode 100644 packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
 create mode 100644 packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts
 create mode 100644 packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
 create mode 100644 packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
 create mode 100644 packages/target-ethers-v5/src/codegen/errors.ts
 create mode 100644 packages/target-web3-v1-test/types/v0.8.9/CustomError.ts
 create mode 100644 packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
 create mode 100644 packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts

diff --git a/contracts/v0.8.9/CustomError.sol b/contracts/v0.8.9/CustomError.sol
new file mode 100644
index 000000000..4508b5a60
--- /dev/null
+++ b/contracts/v0.8.9/CustomError.sol
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-3.0
+pragma solidity ^0.8.4;
+
+/// Insufficient balance for transfer. Needed `required` but only
+/// `available` available.
+/// @param available balance available.
+/// @param required requested amount to transfer.
+error InsufficientBalance(uint256 available, uint256 required);
+
+/// @notice example contract from https://blog.soliditylang.org/2021/04/21/custom-errors/
+contract CustomError {
+    mapping(address => uint) balance;
+
+    function transfer(address to, uint256 amount) public {
+        if (amount > balance[msg.sender])
+            // Error call using named parameters. Equivalent to
+            // revert InsufficientBalance(balance[msg.sender], amount);
+            revert InsufficientBalance({
+                available: balance[msg.sender],
+                required: amount
+            });
+        balance[msg.sender] -= amount;
+        balance[to] += amount;
+    }
+    // ...
+}
diff --git a/packages/target-ethers-v5-test/test/CustomError.test.ts b/packages/target-ethers-v5-test/test/CustomError.test.ts
new file mode 100644
index 000000000..7485c130b
--- /dev/null
+++ b/packages/target-ethers-v5-test/test/CustomError.test.ts
@@ -0,0 +1,48 @@
+import { BigNumber, ethers } from 'ethers'
+import { AssertTrue, IsExact, typedAssert } from 'test-utils'
+
+// import type { TypedCustomEvent } from '../types/common'
+
+import type {
+    CustomError
+} from '../types/v0.8.9/CustomError'
+import { createNewBlockchain, deployContract } from './common'
+
+describe('CustomError support', () => {
+  const chain = createNewBlockchain<CustomError>('CustomError')
+
+  let contract!: CustomError
+
+  beforeEach(async () => {
+    contract = chain.contract
+    const { signer } = chain
+
+    signer.provider.pollingInterval = 100
+    contract = await deployContract<CustomError>(signer, 'CustomError')
+  })
+
+  afterEach(async () => {
+  })
+
+  it.only('typed event import', async () => {
+      try {
+        const foo = await contract.callStatic.transfer('0x0000000000000000000000000000000000000000', 1)
+
+        console.log('in here')
+      } catch (err) {
+          console.log(err)
+          console.log(Object.keys(err as any))
+      }
+    // const filter = contract.errors.Event1(null, null)
+    // const results = (await contract.queryFilter(filter)) as any
+
+    // const results2 = results as Event1Event[]
+    // results2.map((r) => {
+    //   typedAssert(r.args.value1, BigNumber.from(1))
+    //   typedAssert(r.args.value2, BigNumber.from(2))
+    //   typedAssert(r.args[0], BigNumber.from(1))
+    //   typedAssert(r.args[1], BigNumber.from(2))
+    // })
+  })
+
+})
diff --git a/packages/target-ethers-v5-test/test/common.ts b/packages/target-ethers-v5-test/test/common.ts
index 7084b5573..cf5072cc8 100644
--- a/packages/target-ethers-v5-test/test/common.ts
+++ b/packages/target-ethers-v5-test/test/common.ts
@@ -26,7 +26,7 @@ export function createNewBlockchain<TContract>(contractName: string) {
   const ctx: Partial<Ctx> = {}
 
   beforeEach(async () => {
-    const ganache = createGanacheServer({ logging: { quiet: true } })
+    const ganache = createGanacheServer({ logging: { quiet: false } })
 
     await ganache.listen(8545)
 
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
new file mode 100644
index 000000000..566652e32
--- /dev/null
+++ b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
@@ -0,0 +1,60 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+
+import { Contract, Signer, utils } from "ethers";
+import type { Provider } from "@ethersproject/providers";
+import type {
+  TestToken,
+  TestTokenInterface,
+} from "../../../v0.8.9/CustomError/TestToken";
+
+const _abi = [
+  {
+    inputs: [
+      {
+        internalType: "uint256",
+        name: "available",
+        type: "uint256",
+      },
+      {
+        internalType: "uint256",
+        name: "required",
+        type: "uint256",
+      },
+    ],
+    name: "InsufficientBalance",
+    type: "error",
+  },
+  {
+    inputs: [
+      {
+        internalType: "address",
+        name: "to",
+        type: "address",
+      },
+      {
+        internalType: "uint256",
+        name: "amount",
+        type: "uint256",
+      },
+    ],
+    name: "transfer",
+    outputs: [],
+    stateMutability: "nonpayable",
+    type: "function",
+  },
+];
+
+export class TestToken__factory {
+  static readonly abi = _abi;
+  static createInterface(): TestTokenInterface {
+    return new utils.Interface(_abi) as TestTokenInterface;
+  }
+  static connect(
+    address: string,
+    signerOrProvider: Signer | Provider
+  ): TestToken {
+    return new Contract(address, _abi, signerOrProvider) as TestToken;
+  }
+}
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts
new file mode 100644
index 000000000..33edb32a2
--- /dev/null
+++ b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts
@@ -0,0 +1,4 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+export { TestToken__factory } from "./TestToken__factory";
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
new file mode 100644
index 000000000..d7cc71ff6
--- /dev/null
+++ b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
@@ -0,0 +1,65 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+
+import { Contract, Signer, utils } from "ethers";
+import type { Provider } from "@ethersproject/providers";
+import type {
+  CustomError,
+  CustomErrorInterface,
+} from "../../v0.8.9/CustomError";
+
+const _abi = [
+  {
+    inputs: [
+      {
+        internalType: "uint256",
+        name: "magic",
+        type: "uint256",
+      },
+      {
+        internalType: "uint256",
+        name: "available",
+        type: "uint256",
+      },
+      {
+        internalType: "uint256",
+        name: "required",
+        type: "uint256",
+      },
+    ],
+    name: "InsufficientBalance",
+    type: "error",
+  },
+  {
+    inputs: [
+      {
+        internalType: "address",
+        name: "to",
+        type: "address",
+      },
+      {
+        internalType: "uint256",
+        name: "amount",
+        type: "uint256",
+      },
+    ],
+    name: "transfer",
+    outputs: [],
+    stateMutability: "nonpayable",
+    type: "function",
+  },
+];
+
+export class CustomError__factory {
+  static readonly abi = _abi;
+  static createInterface(): CustomErrorInterface {
+    return new utils.Interface(_abi) as CustomErrorInterface;
+  }
+  static connect(
+    address: string,
+    signerOrProvider: Signer | Provider
+  ): CustomError {
+    return new Contract(address, _abi, signerOrProvider) as CustomError;
+  }
+}
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/index.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/index.ts
index 964695c88..9ce92dfec 100644
--- a/packages/target-ethers-v5-test/types/factories/v0.8.9/index.ts
+++ b/packages/target-ethers-v5-test/types/factories/v0.8.9/index.ts
@@ -4,6 +4,7 @@
 export * as kingOfTheHill from "./KingOfTheHill";
 export * as rarity from "./Rarity";
 export * as nested from "./nested";
+export { CustomError__factory } from "./CustomError__factory";
 export { ISimpleToken__factory } from "./ISimpleToken__factory";
 export { Issue552_Reproduction__factory } from "./Issue552_Reproduction__factory";
 export { SimpleToken__factory } from "./SimpleToken__factory";
diff --git a/packages/target-ethers-v5-test/types/index.ts b/packages/target-ethers-v5-test/types/index.ts
index 86c671afb..29f70f9dd 100644
--- a/packages/target-ethers-v5-test/types/index.ts
+++ b/packages/target-ethers-v5-test/types/index.ts
@@ -30,6 +30,8 @@ export type { Payable } from "./v0.6.4/Payable/Payable";
 export { Payable__factory } from "./factories/v0.6.4/Payable/Payable__factory";
 export type { PayableFactory } from "./v0.6.4/Payable/PayableFactory";
 export { PayableFactory__factory } from "./factories/v0.6.4/Payable/PayableFactory__factory";
+export type { CustomError } from "./v0.8.9/CustomError";
+export { CustomError__factory } from "./factories/v0.8.9/CustomError__factory";
 export type { ISimpleToken } from "./v0.8.9/ISimpleToken";
 export { ISimpleToken__factory } from "./factories/v0.8.9/ISimpleToken__factory";
 export type { Issue552_Reproduction } from "./v0.8.9/Issue552_Reproduction";
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesInput.ts b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesInput.ts
index a14041bcd..6af137ebd 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesInput.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesInput.ts
@@ -388,6 +388,8 @@ export interface DataTypesInputInterface extends utils.Interface {
   ): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface DataTypesInput extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesPure.ts b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesPure.ts
index 911257c2e..7de7f3dd6 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesPure.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesPure.ts
@@ -153,6 +153,8 @@ export interface DataTypesPureInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "pure_uint8", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface DataTypesPure extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesView.ts b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesView.ts
index afe48c687..5ddfea9a1 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/DataTypesView.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/DataTypesView.ts
@@ -153,6 +153,8 @@ export interface DataTypesViewInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "view_uint8", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface DataTypesView extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Events.ts b/packages/target-ethers-v5-test/types/v0.6.4/Events.ts
index b9dc14576..24c1489a9 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Events.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Events.ts
@@ -121,6 +121,8 @@ export interface EventsInterface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Event4"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "NoArgsEvent"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "UpdateFrequencySet"): EventFragment;
+
+  errors: {};
 }
 
 export interface AnonEvent1EventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/A.ts b/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/A.ts
index 98287f216..41e7a32bc 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/A.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/A.ts
@@ -19,6 +19,8 @@ export interface AInterface extends utils.Interface {
   };
 
   getEvent(nameOrSignatureOrTopic: "Committed"): EventFragment;
+
+  errors: {};
 }
 
 export interface CommittedEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/B.ts b/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/B.ts
index 2a49529ef..a0f0f3810 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/B.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Issue428_Reproduction/B.ts
@@ -21,6 +21,8 @@ export interface BInterface extends utils.Interface {
 
   getEvent(nameOrSignatureOrTopic: "Committed(uint256)"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Committed(address[])"): EventFragment;
+
+  errors: {};
 }
 
 export interface Committed_uint256_EventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Library/Lib.ts b/packages/target-ethers-v5-test/types/v0.6.4/Library/Lib.ts
index 2bd5f1dfb..87a131f7e 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Library/Lib.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Library/Lib.ts
@@ -32,6 +32,8 @@ export interface LibInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "other", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface Lib extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/LibraryConsumer.ts b/packages/target-ethers-v5-test/types/v0.6.4/LibraryConsumer.ts
index 70fdfd756..439234fc8 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/LibraryConsumer.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/LibraryConsumer.ts
@@ -35,6 +35,8 @@ export interface LibraryConsumerInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "someOther", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface LibraryConsumer extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Name-Mangling/NAME12mangling.ts b/packages/target-ethers-v5-test/types/v0.6.4/Name-Mangling/NAME12mangling.ts
index 143ad127c..f00d9c734 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Name-Mangling/NAME12mangling.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Name-Mangling/NAME12mangling.ts
@@ -34,6 +34,8 @@ export interface NAME12manglingInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "works", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface NAME12mangling extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Overloads.ts b/packages/target-ethers-v5-test/types/v0.6.4/Overloads.ts
index dbe661e54..518e2b35f 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Overloads.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Overloads.ts
@@ -49,6 +49,8 @@ export interface OverloadsInterface extends utils.Interface {
   ): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface Overloads extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Payable/Payable.ts b/packages/target-ethers-v5-test/types/v0.6.4/Payable/Payable.ts
index a04ee47b3..d25a696e0 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Payable/Payable.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Payable/Payable.ts
@@ -51,6 +51,8 @@ export interface PayableInterface extends utils.Interface {
   ): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface Payable extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.6.4/Payable/PayableFactory.ts b/packages/target-ethers-v5-test/types/v0.6.4/Payable/PayableFactory.ts
index 094774c8e..eaa1aaa53 100644
--- a/packages/target-ethers-v5-test/types/v0.6.4/Payable/PayableFactory.ts
+++ b/packages/target-ethers-v5-test/types/v0.6.4/Payable/PayableFactory.ts
@@ -36,6 +36,8 @@ export interface PayableFactoryInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "newPayable", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface PayableFactory extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts b/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
new file mode 100644
index 000000000..709d86fda
--- /dev/null
+++ b/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
@@ -0,0 +1,123 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+import type {
+  BaseContract,
+  BigNumber,
+  BigNumberish,
+  BytesLike,
+  CallOverrides,
+  ContractTransaction,
+  Overrides,
+  PopulatedTransaction,
+  Signer,
+  utils,
+} from "ethers";
+import type {
+  FunctionFragment,
+  Result,
+  ErrorFragment,
+} from "@ethersproject/abi";
+import type { Listener, Provider } from "@ethersproject/providers";
+import type {
+  TypedEventFilter,
+  TypedEvent,
+  TypedListener,
+  OnEvent,
+} from "../common";
+
+export interface CustomErrorInterface extends utils.Interface {
+  functions: {
+    "transfer(address,uint256)": FunctionFragment;
+  };
+
+  getFunction(nameOrSignatureOrTopic: "transfer"): FunctionFragment;
+
+  encodeFunctionData(
+    functionFragment: "transfer",
+    values: [string, BigNumberish]
+  ): string;
+
+  decodeFunctionResult(functionFragment: "transfer", data: BytesLike): Result;
+
+  events: {};
+
+  errors: {
+    "InsufficientBalance(uint256,uint256,uint256)": ErrorFragment;
+  };
+
+  getError(nameOrSignature: "InsufficientBalance"): ErrorFragment;
+}
+
+export interface InsufficientBalanceErrorObject {
+  magic: BigNumber;
+  available: BigNumber;
+  required: BigNumber;
+}
+
+export interface CustomError extends BaseContract {
+  connect(signerOrProvider: Signer | Provider | string): this;
+  attach(addressOrName: string): this;
+  deployed(): Promise<this>;
+
+  interface: CustomErrorInterface;
+
+  queryFilter<TEvent extends TypedEvent>(
+    event: TypedEventFilter<TEvent>,
+    fromBlockOrBlockhash?: string | number | undefined,
+    toBlock?: string | number | undefined
+  ): Promise<Array<TEvent>>;
+
+  listeners<TEvent extends TypedEvent>(
+    eventFilter?: TypedEventFilter<TEvent>
+  ): Array<TypedListener<TEvent>>;
+  listeners(eventName?: string): Array<Listener>;
+  removeAllListeners<TEvent extends TypedEvent>(
+    eventFilter: TypedEventFilter<TEvent>
+  ): this;
+  removeAllListeners(eventName?: string): this;
+  off: OnEvent<this>;
+  on: OnEvent<this>;
+  once: OnEvent<this>;
+  removeListener: OnEvent<this>;
+
+  functions: {
+    transfer(
+      to: string,
+      amount: BigNumberish,
+      overrides?: Overrides & { from?: string | Promise<string> }
+    ): Promise<ContractTransaction>;
+  };
+
+  transfer(
+    to: string,
+    amount: BigNumberish,
+    overrides?: Overrides & { from?: string | Promise<string> }
+  ): Promise<ContractTransaction>;
+
+  callStatic: {
+    transfer(
+      to: string,
+      amount: BigNumberish,
+      overrides?: CallOverrides
+    ): Promise<void>;
+  };
+
+  filters: {};
+
+  estimateGas: {
+    transfer(
+      to: string,
+      amount: BigNumberish,
+      overrides?: Overrides & { from?: string | Promise<string> }
+    ): Promise<BigNumber>;
+  };
+
+  populateTransaction: {
+    transfer(
+      to: string,
+      amount: BigNumberish,
+      overrides?: Overrides & { from?: string | Promise<string> }
+    ): Promise<PopulatedTransaction>;
+  };
+}
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/ISimpleToken.ts b/packages/target-ethers-v5-test/types/v0.8.9/ISimpleToken.ts
index 601e12db8..7e19915ff 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/ISimpleToken.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/ISimpleToken.ts
@@ -37,6 +37,8 @@ export interface ISimpleTokenInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "transfer", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface ISimpleToken extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Issue552_Reproduction.ts b/packages/target-ethers-v5-test/types/v0.8.9/Issue552_Reproduction.ts
index afb3a8f9f..f6803cde9 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Issue552_Reproduction.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Issue552_Reproduction.ts
@@ -78,6 +78,8 @@ export interface Issue552_ReproductionInterface extends utils.Interface {
   ): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface Issue552_Reproduction extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/KingOfTheHill.ts b/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/KingOfTheHill.ts
index f2d13fffe..4b0a5f4ce 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/KingOfTheHill.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/KingOfTheHill.ts
@@ -18,6 +18,7 @@ import type {
   FunctionFragment,
   Result,
   EventFragment,
+  ErrorFragment,
 } from "@ethersproject/abi";
 import type { Listener, Provider } from "@ethersproject/providers";
 import type {
@@ -63,6 +64,12 @@ export interface KingOfTheHillInterface extends utils.Interface {
   };
 
   getEvent(nameOrSignatureOrTopic: "HighestBidIncreased"): EventFragment;
+
+  errors: {
+    "BidNotHighEnough(uint256,uint256)": ErrorFragment;
+  };
+
+  getError(nameOrSignature: "BidNotHighEnough"): ErrorFragment;
 }
 
 export interface HighestBidIncreasedEventObject {
@@ -76,6 +83,11 @@ export type HighestBidIncreasedEvent = TypedEvent<
 export type HighestBidIncreasedEventFilter =
   TypedEventFilter<HighestBidIncreasedEvent>;
 
+export interface BidNotHighEnoughErrorObject {
+  value: BigNumber;
+  highestBidValue: BigNumber;
+}
+
 export interface KingOfTheHill extends BaseContract {
   connect(signerOrProvider: Signer | Provider | string): this;
   attach(addressOrName: string): this;
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/Withdrawable.ts b/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/Withdrawable.ts
index dc139bedf..b128e3fe2 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/Withdrawable.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/KingOfTheHill/Withdrawable.ts
@@ -33,6 +33,8 @@ export interface WithdrawableInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "withdraw", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface Withdrawable extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721.ts
index 6a51a1c99..166a7afa7 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721.ts
@@ -123,6 +123,8 @@ export interface ERC721Interface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Approval"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "ApprovalForAll"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721Enumerable.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721Enumerable.ts
index 01e5ca999..b35969aa5 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721Enumerable.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/ERC721Enumerable.ts
@@ -153,6 +153,8 @@ export interface ERC721EnumerableInterface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Approval"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "ApprovalForAll"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721.ts
index 437b6d1d3..9a8682793 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721.ts
@@ -123,6 +123,8 @@ export interface IERC721Interface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Approval"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "ApprovalForAll"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Enumerable.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Enumerable.ts
index 2cb29f60e..8e0686edf 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Enumerable.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Enumerable.ts
@@ -153,6 +153,8 @@ export interface IERC721EnumerableInterface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Approval"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "ApprovalForAll"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Receiver.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Receiver.ts
index d348d3663..12c09d38e 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Receiver.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/IERC721Receiver.ts
@@ -40,6 +40,8 @@ export interface IERC721ReceiverInterface extends utils.Interface {
   ): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface IERC721Receiver extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/Rarity.ts b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/Rarity.ts
index a77ce527e..a796992f2 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/Rarity/Rarity.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/Rarity/Rarity.ts
@@ -248,6 +248,8 @@ export interface RarityInterface extends utils.Interface {
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "leveled"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "summoned"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/SimpleToken.ts b/packages/target-ethers-v5-test/types/v0.8.9/SimpleToken.ts
index 89978520c..326032ec3 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/SimpleToken.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/SimpleToken.ts
@@ -37,6 +37,8 @@ export interface SimpleTokenInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "transfer", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface SimpleToken extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/index.ts b/packages/target-ethers-v5-test/types/v0.8.9/index.ts
index 25c6eeca5..b9e9025e9 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/index.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/index.ts
@@ -7,6 +7,7 @@ import type * as rarity from "./Rarity";
 export type { rarity };
 import type * as nested from "./nested";
 export type { nested };
+export type { CustomError } from "./CustomError";
 export type { ISimpleToken } from "./ISimpleToken";
 export type { Issue552_Reproduction } from "./Issue552_Reproduction";
 export type { SimpleToken } from "./SimpleToken";
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/nested/a/NestedLibrary.ts b/packages/target-ethers-v5-test/types/v0.8.9/nested/a/NestedLibrary.ts
index 3bc95b6bb..e68e30463 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/nested/a/NestedLibrary.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/nested/a/NestedLibrary.ts
@@ -31,6 +31,8 @@ export interface NestedLibraryInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "getValue", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface NestedLibrary extends BaseContract {
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/nested/b/NestedLibrary.ts b/packages/target-ethers-v5-test/types/v0.8.9/nested/b/NestedLibrary.ts
index 5eef3ca0b..3e2e3b3e2 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/nested/b/NestedLibrary.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/nested/b/NestedLibrary.ts
@@ -31,6 +31,8 @@ export interface NestedLibraryInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "getValue", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface NestedLibrary extends BaseContract {
diff --git a/packages/target-ethers-v5/src/codegen/errors.ts b/packages/target-ethers-v5/src/codegen/errors.ts
new file mode 100644
index 000000000..ea2717bd8
--- /dev/null
+++ b/packages/target-ethers-v5/src/codegen/errors.ts
@@ -0,0 +1,64 @@
+import {
+    createPositionalIdentifier,
+    CustomErrorDeclaration,
+    getSignatureForFn,
+  } from 'typechain'
+  
+  import { generateOutputComplexTypeAsArray, generateOutputComplexTypesAsObject } from './types'
+  
+  
+  
+  export function generateErrorTypeExports(errors: CustomErrorDeclaration[]) {
+    if (errors.length === 1) {
+      return generateErrorTypeExport(errors[0], false)
+    } else {
+      return errors.map((e) => generateErrorTypeExport(e, true)).join('\n')
+    }
+  }
+  
+  
+  function generateErrorTypeExport(error: CustomErrorDeclaration, includeArgTypes: boolean) {
+    const components = error.inputs.map((input, i) => ({ name: input.name ?? `arg${i.toString()}`, type: input.type }))
+    const objectOutput = generateOutputComplexTypesAsObject(components, { useStructs: true }) || '{}'
+  
+    const identifier = generateErrorIdentifier(error, { includeArgTypes })
+  
+    return `
+      export interface ${identifier}Object ${objectOutput};
+    `
+  }
+  
+  export function generateInterfaceErrorDescription(error: CustomErrorDeclaration): string {
+    return `'${generateErrorSignature(error)}': ErrorFragment;`
+  }
+  
+  export function generateErrorSignature(error: CustomErrorDeclaration): string {
+    return `${error.name}(${error.inputs.map((input: any) => input.type.originalType).join(',')})`
+  }
+  
+  export function generateErrorInputs(errorArgs: CustomErrorDeclaration["inputs"]) {
+    if (errorArgs.length === 0) {
+      return ''
+    }
+    return (
+      errorArgs
+        .map((arg, index) => {
+          return createPositionalIdentifier(arg.name)
+        })
+        .join(', ') + ', '
+    )
+  }
+  
+  export function generateGetError(error: CustomErrorDeclaration, useSignature: boolean): string {
+    return `getError(nameOrSignature: '${
+      useSignature ? generateErrorSignature(error) : error.name
+    }'): ErrorFragment;`
+  }
+  
+  function generateErrorIdentifier(error: CustomErrorDeclaration, { includeArgTypes }: { includeArgTypes?: boolean } = {}) {
+    if (includeArgTypes) {
+      return getSignatureForFn(error) + '_Error'
+    } else {
+      return error.name + 'Error'
+    }
+  }
diff --git a/packages/target-ethers-v5/src/codegen/index.ts b/packages/target-ethers-v5/src/codegen/index.ts
index de8fd9e60..0e3c5ff75 100644
--- a/packages/target-ethers-v5/src/codegen/index.ts
+++ b/packages/target-ethers-v5/src/codegen/index.ts
@@ -5,6 +5,7 @@ import {
   Contract,
   createImportsForUsedIdentifiers,
   createImportTypeDeclaration,
+  CustomErrorDeclaration,
   EventDeclaration,
   FunctionDeclaration,
   StructType,
@@ -19,6 +20,11 @@ import {
   generateGetEvent,
   generateInterfaceEventDescription,
 } from './events'
+import {
+  generateInterfaceErrorDescription,
+  generateGetError,
+  generateErrorTypeExports
+} from './errors'
 import {
   codegenFunctions,
   generateDecodeFunctionResultOverload,
@@ -69,9 +75,20 @@ export function codegenContractTypings(contract: Contract, codegenConfig: Codege
     ${values(contract.events)
       .flatMap((v) => processDeclaration(v, alwaysGenerateOverloads, generateGetEvent))
       .join('\n')}
+
+      errors: {
+        ${values(contract.errors)
+          .flatMap((v) => v.map(generateInterfaceErrorDescription))
+          .join('\n')}
+      };
+
+      ${values(contract.errors)
+        .flatMap((v) => processDeclaration(v, alwaysGenerateOverloads, generateGetError))
+        .join('\n')}
   }
 
   ${values(contract.events).map(generateEventTypeExports).join('\n')}
+  ${values(contract.errors).map(generateErrorTypeExports).join('\n')}
 
   export interface ${contract.name} extends BaseContract {
     ${codegenConfig.discriminateTypes ? `contractName: '${contract.name}';\n` : ``}
@@ -137,7 +154,7 @@ export function codegenContractTypings(contract: Contract, codegenConfig: Codege
           'Signer',
           'utils',
         ],
-        'type @ethersproject/abi': ['FunctionFragment', 'Result', 'EventFragment'],
+        'type @ethersproject/abi': ['FunctionFragment', 'Result', 'EventFragment', 'ErrorFragment'],
         'type @ethersproject/providers': ['Listener', 'Provider'],
       },
       source,
@@ -375,7 +392,7 @@ function generateLibraryAddressesInterface(contract: Contract, bytecode: Bytecod
  * @param stringGen - function generating source code based on the declaration
  * @returns generated source code
  */
-function processDeclaration<D extends FunctionDeclaration | EventDeclaration>(
+function processDeclaration<D extends FunctionDeclaration | EventDeclaration | CustomErrorDeclaration>(
   fns: D[],
   forceGenerateOverloads: boolean,
   stringGen: (fn: D, useSignature: boolean) => string,
diff --git a/packages/target-web3-v1-test/types/v0.8.9/CustomError.ts b/packages/target-web3-v1-test/types/v0.8.9/CustomError.ts
new file mode 100644
index 000000000..5beec33e5
--- /dev/null
+++ b/packages/target-web3-v1-test/types/v0.8.9/CustomError.ts
@@ -0,0 +1,40 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+
+import type BN from "bn.js";
+import type { ContractOptions } from "web3-eth-contract";
+import type { EventLog } from "web3-core";
+import type { EventEmitter } from "events";
+import type {
+  Callback,
+  PayableTransactionObject,
+  NonPayableTransactionObject,
+  BlockType,
+  ContractEventLog,
+  BaseContract,
+} from "../types";
+
+export interface EventOptions {
+  filter?: object;
+  fromBlock?: BlockType;
+  topics?: string[];
+}
+
+export interface CustomError extends BaseContract {
+  constructor(
+    jsonInterface: any[],
+    address?: string,
+    options?: ContractOptions
+  ): CustomError;
+  clone(): CustomError;
+  methods: {
+    transfer(
+      to: string,
+      amount: number | string | BN
+    ): NonPayableTransactionObject<void>;
+  };
+  events: {
+    allEvents(options?: EventOptions, cb?: Callback<EventLog>): EventEmitter;
+  };
+}
diff --git a/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts b/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
new file mode 100644
index 000000000..c925f1c15
--- /dev/null
+++ b/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
@@ -0,0 +1,40 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+
+import type BN from "bn.js";
+import type { ContractOptions } from "web3-eth-contract";
+import type { EventLog } from "web3-core";
+import type { EventEmitter } from "events";
+import type {
+  Callback,
+  PayableTransactionObject,
+  NonPayableTransactionObject,
+  BlockType,
+  ContractEventLog,
+  BaseContract,
+} from "../../types";
+
+export interface EventOptions {
+  filter?: object;
+  fromBlock?: BlockType;
+  topics?: string[];
+}
+
+export interface TestToken extends BaseContract {
+  constructor(
+    jsonInterface: any[],
+    address?: string,
+    options?: ContractOptions
+  ): TestToken;
+  clone(): TestToken;
+  methods: {
+    transfer(
+      to: string,
+      amount: number | string | BN
+    ): NonPayableTransactionObject<void>;
+  };
+  events: {
+    allEvents(options?: EventOptions, cb?: Callback<EventLog>): EventEmitter;
+  };
+}
diff --git a/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts b/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts
new file mode 100644
index 000000000..14ee95744
--- /dev/null
+++ b/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts
@@ -0,0 +1,4 @@
+/* Autogenerated file. Do not edit manually. */
+/* tslint:disable */
+/* eslint-disable */
+export type { TestToken } from "./TestToken";
diff --git a/packages/target-web3-v1-test/types/v0.8.9/index.ts b/packages/target-web3-v1-test/types/v0.8.9/index.ts
index 25c6eeca5..b9e9025e9 100644
--- a/packages/target-web3-v1-test/types/v0.8.9/index.ts
+++ b/packages/target-web3-v1-test/types/v0.8.9/index.ts
@@ -7,6 +7,7 @@ import type * as rarity from "./Rarity";
 export type { rarity };
 import type * as nested from "./nested";
 export type { nested };
+export type { CustomError } from "./CustomError";
 export type { ISimpleToken } from "./ISimpleToken";
 export type { Issue552_Reproduction } from "./Issue552_Reproduction";
 export type { SimpleToken } from "./SimpleToken";
diff --git a/packages/typechain/src/parser/abiParser.ts b/packages/typechain/src/parser/abiParser.ts
index 0f054ed36..bab958c16 100644
--- a/packages/typechain/src/parser/abiParser.ts
+++ b/packages/typechain/src/parser/abiParser.ts
@@ -61,6 +61,7 @@ export interface Contract {
   constructor: FunctionWithoutOutputDeclaration[]
   functions: Dictionary<FunctionDeclaration[]>
   events: Dictionary<EventDeclaration[]>
+  errors: Dictionary<CustomErrorDeclaration[]>
   structs: Dictionary<StructType[]>
   documentation?:
     | {
@@ -88,6 +89,12 @@ export interface RawAbiDefinition {
   type: string
 }
 
+export interface CustomErrorDeclaration {
+  name: string
+  inputs: AbiParameter[]
+  documentation?: FunctionDocumentation | undefined // should omit `return` from FunctionDocumentation?
+}
+
 export interface EventDeclaration {
   name: string
   isAnonymous: boolean
@@ -150,6 +157,7 @@ export function parse(abi: RawAbiDefinition[], path: string, documentation?: Doc
   let fallback: FunctionWithoutInputDeclaration | undefined
   const functions: FunctionDeclaration[] = []
   const events: EventDeclaration[] = []
+  const errors: CustomErrorDeclaration[] = []
 
   const structs: StructType[] = []
   function registerStruct(newStruct: StructType) {
@@ -196,6 +204,11 @@ export function parse(abi: RawAbiDefinition[], path: string, documentation?: Doc
       return
     }
 
+    if (abiPiece.type === 'error') {
+      errors.push(parseCustomErrorDeclaration(abiPiece, registerStruct, documentation))
+      return
+    }
+
     debug(`Unrecognized abi element: ${abiPiece.type}`)
   })
 
@@ -205,6 +218,7 @@ export function parse(abi: RawAbiDefinition[], path: string, documentation?: Doc
     constructor: constructors,
     functions: groupBy(functions, (f) => f.name),
     events: groupBy(events, (e) => e.name),
+    errors: groupBy(errors, (e) => e.name),
     structs: groupBy(structs, (e) => e.structName && e.structName.toString()),
     documentation: documentation ? omit(documentation, ['methods']) : undefined,
   }
@@ -299,6 +313,19 @@ function parseFallback(
   }
 }
 
+export function parseCustomErrorDeclaration(
+  abiPiece: RawAbiDefinition,
+  registerStruct: (struct: StructType) => void,
+  documentation?: DocumentationResult,
+): CustomErrorDeclaration {
+  debug(`Parsing function declaration "${abiPiece.name}"`)
+  return {
+    name: abiPiece.name,
+    inputs: abiPiece.inputs.map(parseRawAbiParameter.bind(null, registerStruct)),
+    documentation: getFunctionDocumentation(abiPiece, documentation),
+  }
+}
+
 function parseFunctionDeclaration(
   abiPiece: RawAbiDefinition,
   registerStruct: (struct: StructType) => void,
diff --git a/packages/typechain/src/utils/signatures.ts b/packages/typechain/src/utils/signatures.ts
index e9717398d..4da9fc896 100644
--- a/packages/typechain/src/utils/signatures.ts
+++ b/packages/typechain/src/utils/signatures.ts
@@ -1,4 +1,4 @@
-import { AbiParameter, EventDeclaration, FunctionDeclaration } from '../parser/abiParser'
+import { AbiParameter, CustomErrorDeclaration, EventDeclaration, FunctionDeclaration } from '../parser/abiParser'
 import { ArrayType, TupleType } from '../parser/parseEvmType'
 
 export function getFullSignatureAsSymbolForEvent(event: EventDeclaration): string {
@@ -32,6 +32,6 @@ export function getArgumentForSignature(argument: AbiParameter): string {
   }
 }
 
-export function getSignatureForFn(fn: FunctionDeclaration): string {
+export function getSignatureForFn(fn: FunctionDeclaration | CustomErrorDeclaration): string {
   return `${fn.name}(${fn.inputs.map((i) => getArgumentForSignature(i)).join(',')})`
 }
diff --git a/packages/typechain/test/parser/abiParser.test.ts b/packages/typechain/test/parser/abiParser.test.ts
index ed4e67423..43671f125 100644
--- a/packages/typechain/test/parser/abiParser.test.ts
+++ b/packages/typechain/test/parser/abiParser.test.ts
@@ -12,6 +12,7 @@ import {
   isConstant,
   isConstantFn,
   parse,
+  parseCustomErrorDeclaration,
   parseEvent,
   RawAbiDefinition,
   RawEventAbiDefinition,
@@ -368,6 +369,37 @@ describe('parseEvent', () => {
   })
 })
 
+describe('parseError', () => {
+  it('works', () => {
+    const expectedError = {
+      inputs: [
+        {
+          internalType: "uint256",
+          name: "magic",
+          type: "uint256"
+        },
+        {
+          internalType: "address",
+          name: "target",
+          type: "address"
+        },
+      ],
+      "name": "InsufficientBalance",
+      "type": "error"
+    } as RawAbiDefinition
+    const parsedError = parseCustomErrorDeclaration(expectedError, () => {})
+
+    expect(parsedError).toEqual({
+      name: 'InsufficientBalance',
+      inputs: [
+        { name: 'magic', type: { type: 'uinteger', bits: 256, originalType: 'uint256' } },
+        { name: 'target', type: { type: 'address', originalType: 'address' } },
+      ],
+      documentation: undefined
+    })
+  })
+})
+
 describe('parse', () => {
   describe('functions', () => {
     const abiPiece = {
@@ -504,6 +536,7 @@ describe('parse', () => {
         documentation: undefined,
         functions: {},
         structs: {},
+        errors: {},
         name: 'Sc1',
         rawName: 'sc1',
         path: [],

From 1edb272bbe73a3921e1c5cb5bd56c2dcc04909fe Mon Sep 17 00:00:00 2001
From: fredlacs <32464905+fredlacs@users.noreply.github.com>
Date: Sun, 1 May 2022 15:22:42 +0100
Subject: [PATCH 2/5] Cleanup unit test

---
 .../test/CustomError.test.ts                  | 30 +++++--------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/packages/target-ethers-v5-test/test/CustomError.test.ts b/packages/target-ethers-v5-test/test/CustomError.test.ts
index 7485c130b..77a48b971 100644
--- a/packages/target-ethers-v5-test/test/CustomError.test.ts
+++ b/packages/target-ethers-v5-test/test/CustomError.test.ts
@@ -1,11 +1,7 @@
 import { BigNumber, ethers } from 'ethers'
 import { AssertTrue, IsExact, typedAssert } from 'test-utils'
 
-// import type { TypedCustomEvent } from '../types/common'
-
-import type {
-    CustomError
-} from '../types/v0.8.9/CustomError'
+import type { CustomError } from '../types/v0.8.9/CustomError'
 import { createNewBlockchain, deployContract } from './common'
 
 describe('CustomError support', () => {
@@ -24,25 +20,15 @@ describe('CustomError support', () => {
   afterEach(async () => {
   })
 
-  it.only('typed event import', async () => {
+  it('typed error import', async () => {
       try {
-        const foo = await contract.callStatic.transfer('0x0000000000000000000000000000000000000000', 1)
-
-        console.log('in here')
+        await contract.callStatic.transfer('0x0000000000000000000000000000000000000000', 1)
       } catch (err) {
-          console.log(err)
-          console.log(Object.keys(err as any))
+        const expectedError = contract.interface.errors['InsufficientBalance(uint256,uint256,uint256)']
+        console.log(expectedError)
+        console.log(err)
+        // TODO: still wip on how to best consume the errors here
+        // if(err.reason !== expectedError.)
       }
-    // const filter = contract.errors.Event1(null, null)
-    // const results = (await contract.queryFilter(filter)) as any
-
-    // const results2 = results as Event1Event[]
-    // results2.map((r) => {
-    //   typedAssert(r.args.value1, BigNumber.from(1))
-    //   typedAssert(r.args.value2, BigNumber.from(2))
-    //   typedAssert(r.args[0], BigNumber.from(1))
-    //   typedAssert(r.args[1], BigNumber.from(2))
-    // })
   })
-
 })

From 7b9c84cb8b2adba0bd41e92210672366953869f8 Mon Sep 17 00:00:00 2001
From: fredlacs <32464905+fredlacs@users.noreply.github.com>
Date: Sun, 1 May 2022 15:43:04 +0100
Subject: [PATCH 3/5] Lint and cleanup

---
 .../hardhat-test/typechain-types/Counter.ts   |   2 +
 packages/hardhat-test/typechain-types/Demo.ts |   2 +
 .../typechain-types/StructsInConstructor.ts   |   2 +
 .../artifacts/contracts/EdgeCases.ts          |   2 +
 .../artifacts/contracts/TestContract.ts       |   2 +
 .../artifacts/contracts/TestContract1.ts      |   2 +
 .../artifacts/contracts/lib/SafeMath.ts       |   2 +
 .../externalArtifacts/ERC20.ts                |   2 +
 .../test/CustomError.test.ts                  |  24 ++--
 packages/target-ethers-v5-test/test/common.ts |   2 +-
 .../v0.8.9/CustomError/TestToken__factory.ts  |  60 ----------
 .../factories/v0.8.9/CustomError/index.ts     |   4 -
 .../factories/v0.8.9/CustomError__factory.ts  |   5 -
 .../types/v0.8.9/CustomError.ts               |   3 +-
 .../target-ethers-v5/src/codegen/errors.ts    | 112 +++++++++---------
 .../target-ethers-v5/src/codegen/index.ts     |   6 +-
 .../target-ethers-v5/test/generation.test.ts  |   1 +
 .../typechain/test/parser/abiParser.test.ts   |  18 +--
 18 files changed, 92 insertions(+), 159 deletions(-)
 delete mode 100644 packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
 delete mode 100644 packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts

diff --git a/packages/hardhat-test/typechain-types/Counter.ts b/packages/hardhat-test/typechain-types/Counter.ts
index e33aaaeb8..bc4dfbb79 100644
--- a/packages/hardhat-test/typechain-types/Counter.ts
+++ b/packages/hardhat-test/typechain-types/Counter.ts
@@ -49,6 +49,8 @@ export interface CounterInterface extends utils.Interface {
   };
 
   getEvent(nameOrSignatureOrTopic: "CountedTo"): EventFragment;
+
+  errors: {};
 }
 
 export interface CountedToEventObject {
diff --git a/packages/hardhat-test/typechain-types/Demo.ts b/packages/hardhat-test/typechain-types/Demo.ts
index fb66a8f88..b73ae05ab 100644
--- a/packages/hardhat-test/typechain-types/Demo.ts
+++ b/packages/hardhat-test/typechain-types/Demo.ts
@@ -37,6 +37,8 @@ export interface DemoInterface extends utils.Interface {
   functions: {};
 
   events: {};
+
+  errors: {};
 }
 
 export interface Demo extends BaseContract {
diff --git a/packages/hardhat-test/typechain-types/StructsInConstructor.ts b/packages/hardhat-test/typechain-types/StructsInConstructor.ts
index 386dabbc2..ab9cc3df6 100644
--- a/packages/hardhat-test/typechain-types/StructsInConstructor.ts
+++ b/packages/hardhat-test/typechain-types/StructsInConstructor.ts
@@ -28,6 +28,8 @@ export interface StructsInConstructorInterface extends utils.Interface {
   functions: {};
 
   events: {};
+
+  errors: {};
 }
 
 export interface StructsInConstructor extends BaseContract {
diff --git a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/EdgeCases.ts b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/EdgeCases.ts
index 8eba81138..10a6895dc 100644
--- a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/EdgeCases.ts
+++ b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/EdgeCases.ts
@@ -15,6 +15,8 @@ export interface EdgeCasesInterface extends utils.Interface {
   functions: {};
 
   events: {};
+
+  errors: {};
 }
 
 export interface EdgeCases extends BaseContract {
diff --git a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract.ts b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract.ts
index db01ca653..2345e16d5 100644
--- a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract.ts
+++ b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract.ts
@@ -15,6 +15,8 @@ export interface TestContractInterface extends utils.Interface {
   functions: {};
 
   events: {};
+
+  errors: {};
 }
 
 export interface TestContract extends BaseContract {
diff --git a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract1.ts b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract1.ts
index dff563516..ec51c9aff 100644
--- a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract1.ts
+++ b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/TestContract1.ts
@@ -15,6 +15,8 @@ export interface TestContract1Interface extends utils.Interface {
   functions: {};
 
   events: {};
+
+  errors: {};
 }
 
 export interface TestContract1 extends BaseContract {
diff --git a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/lib/SafeMath.ts b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/lib/SafeMath.ts
index 279a9ccff..741845129 100644
--- a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/lib/SafeMath.ts
+++ b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/artifacts/contracts/lib/SafeMath.ts
@@ -55,6 +55,8 @@ export interface SafeMathInterface extends utils.Interface {
   decodeFunctionResult(functionFragment: "sub", data: BytesLike): Result;
 
   events: {};
+
+  errors: {};
 }
 
 export interface SafeMath extends BaseContract {
diff --git a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/externalArtifacts/ERC20.ts b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/externalArtifacts/ERC20.ts
index b4cdaf3c1..285ddd955 100644
--- a/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/externalArtifacts/ERC20.ts
+++ b/packages/hardhat/test/fixture-projects/hardhat-project/typechain-types/externalArtifacts/ERC20.ts
@@ -120,6 +120,8 @@ export interface ERC20Interface extends utils.Interface {
 
   getEvent(nameOrSignatureOrTopic: "Approval"): EventFragment;
   getEvent(nameOrSignatureOrTopic: "Transfer"): EventFragment;
+
+  errors: {};
 }
 
 export interface ApprovalEventObject {
diff --git a/packages/target-ethers-v5-test/test/CustomError.test.ts b/packages/target-ethers-v5-test/test/CustomError.test.ts
index 77a48b971..4e4ff4361 100644
--- a/packages/target-ethers-v5-test/test/CustomError.test.ts
+++ b/packages/target-ethers-v5-test/test/CustomError.test.ts
@@ -1,6 +1,3 @@
-import { BigNumber, ethers } from 'ethers'
-import { AssertTrue, IsExact, typedAssert } from 'test-utils'
-
 import type { CustomError } from '../types/v0.8.9/CustomError'
 import { createNewBlockchain, deployContract } from './common'
 
@@ -17,18 +14,17 @@ describe('CustomError support', () => {
     contract = await deployContract<CustomError>(signer, 'CustomError')
   })
 
-  afterEach(async () => {
-  })
+  afterEach(async () => {})
 
   it('typed error import', async () => {
-      try {
-        await contract.callStatic.transfer('0x0000000000000000000000000000000000000000', 1)
-      } catch (err) {
-        const expectedError = contract.interface.errors['InsufficientBalance(uint256,uint256,uint256)']
-        console.log(expectedError)
-        console.log(err)
-        // TODO: still wip on how to best consume the errors here
-        // if(err.reason !== expectedError.)
-      }
+    try {
+      await contract.callStatic.transfer('0x0000000000000000000000000000000000000000', 1)
+    } catch (err) {
+      const expectedError = contract.interface.errors['InsufficientBalance(uint256,uint256)']
+      // eslint-disable-next-line no-console
+      console.log(expectedError, err)
+      // TODO: still wip on how to best consume the errors here
+      // if(err.reason !== expectedError.)
+    }
   })
 })
diff --git a/packages/target-ethers-v5-test/test/common.ts b/packages/target-ethers-v5-test/test/common.ts
index cf5072cc8..7084b5573 100644
--- a/packages/target-ethers-v5-test/test/common.ts
+++ b/packages/target-ethers-v5-test/test/common.ts
@@ -26,7 +26,7 @@ export function createNewBlockchain<TContract>(contractName: string) {
   const ctx: Partial<Ctx> = {}
 
   beforeEach(async () => {
-    const ganache = createGanacheServer({ logging: { quiet: false } })
+    const ganache = createGanacheServer({ logging: { quiet: true } })
 
     await ganache.listen(8545)
 
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
deleted file mode 100644
index 566652e32..000000000
--- a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/TestToken__factory.ts
+++ /dev/null
@@ -1,60 +0,0 @@
-/* Autogenerated file. Do not edit manually. */
-/* tslint:disable */
-/* eslint-disable */
-
-import { Contract, Signer, utils } from "ethers";
-import type { Provider } from "@ethersproject/providers";
-import type {
-  TestToken,
-  TestTokenInterface,
-} from "../../../v0.8.9/CustomError/TestToken";
-
-const _abi = [
-  {
-    inputs: [
-      {
-        internalType: "uint256",
-        name: "available",
-        type: "uint256",
-      },
-      {
-        internalType: "uint256",
-        name: "required",
-        type: "uint256",
-      },
-    ],
-    name: "InsufficientBalance",
-    type: "error",
-  },
-  {
-    inputs: [
-      {
-        internalType: "address",
-        name: "to",
-        type: "address",
-      },
-      {
-        internalType: "uint256",
-        name: "amount",
-        type: "uint256",
-      },
-    ],
-    name: "transfer",
-    outputs: [],
-    stateMutability: "nonpayable",
-    type: "function",
-  },
-];
-
-export class TestToken__factory {
-  static readonly abi = _abi;
-  static createInterface(): TestTokenInterface {
-    return new utils.Interface(_abi) as TestTokenInterface;
-  }
-  static connect(
-    address: string,
-    signerOrProvider: Signer | Provider
-  ): TestToken {
-    return new Contract(address, _abi, signerOrProvider) as TestToken;
-  }
-}
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts
deleted file mode 100644
index 33edb32a2..000000000
--- a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError/index.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/* Autogenerated file. Do not edit manually. */
-/* tslint:disable */
-/* eslint-disable */
-export { TestToken__factory } from "./TestToken__factory";
diff --git a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
index d7cc71ff6..fad383002 100644
--- a/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
+++ b/packages/target-ethers-v5-test/types/factories/v0.8.9/CustomError__factory.ts
@@ -12,11 +12,6 @@ import type {
 const _abi = [
   {
     inputs: [
-      {
-        internalType: "uint256",
-        name: "magic",
-        type: "uint256",
-      },
       {
         internalType: "uint256",
         name: "available",
diff --git a/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts b/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
index 709d86fda..16782e6cd 100644
--- a/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
+++ b/packages/target-ethers-v5-test/types/v0.8.9/CustomError.ts
@@ -43,14 +43,13 @@ export interface CustomErrorInterface extends utils.Interface {
   events: {};
 
   errors: {
-    "InsufficientBalance(uint256,uint256,uint256)": ErrorFragment;
+    "InsufficientBalance(uint256,uint256)": ErrorFragment;
   };
 
   getError(nameOrSignature: "InsufficientBalance"): ErrorFragment;
 }
 
 export interface InsufficientBalanceErrorObject {
-  magic: BigNumber;
   available: BigNumber;
   required: BigNumber;
 }
diff --git a/packages/target-ethers-v5/src/codegen/errors.ts b/packages/target-ethers-v5/src/codegen/errors.ts
index ea2717bd8..546feee0f 100644
--- a/packages/target-ethers-v5/src/codegen/errors.ts
+++ b/packages/target-ethers-v5/src/codegen/errors.ts
@@ -1,64 +1,58 @@
-import {
-    createPositionalIdentifier,
-    CustomErrorDeclaration,
-    getSignatureForFn,
-  } from 'typechain'
-  
-  import { generateOutputComplexTypeAsArray, generateOutputComplexTypesAsObject } from './types'
-  
-  
-  
-  export function generateErrorTypeExports(errors: CustomErrorDeclaration[]) {
-    if (errors.length === 1) {
-      return generateErrorTypeExport(errors[0], false)
-    } else {
-      return errors.map((e) => generateErrorTypeExport(e, true)).join('\n')
-    }
+import { createPositionalIdentifier, CustomErrorDeclaration, getSignatureForFn } from 'typechain'
+
+import { generateOutputComplexTypesAsObject } from './types'
+
+export function generateErrorTypeExports(errors: CustomErrorDeclaration[]) {
+  if (errors.length === 1) {
+    return generateErrorTypeExport(errors[0], false)
+  } else {
+    return errors.map((e) => generateErrorTypeExport(e, true)).join('\n')
   }
-  
-  
-  function generateErrorTypeExport(error: CustomErrorDeclaration, includeArgTypes: boolean) {
-    const components = error.inputs.map((input, i) => ({ name: input.name ?? `arg${i.toString()}`, type: input.type }))
-    const objectOutput = generateOutputComplexTypesAsObject(components, { useStructs: true }) || '{}'
-  
-    const identifier = generateErrorIdentifier(error, { includeArgTypes })
-  
-    return `
+}
+
+function generateErrorTypeExport(error: CustomErrorDeclaration, includeArgTypes: boolean) {
+  const components = error.inputs.map((input) => ({ name: input.name, type: input.type }))
+  const objectOutput = generateOutputComplexTypesAsObject(components, { useStructs: true }) || '{}'
+
+  const identifier = generateErrorIdentifier(error, { includeArgTypes })
+
+  return `
       export interface ${identifier}Object ${objectOutput};
     `
+}
+
+export function generateInterfaceErrorDescription(error: CustomErrorDeclaration): string {
+  return `'${generateErrorSignature(error)}': ErrorFragment;`
+}
+
+export function generateErrorSignature(error: CustomErrorDeclaration): string {
+  return `${error.name}(${error.inputs.map((input: any) => input.type.originalType).join(',')})`
+}
+
+export function generateErrorInputs(errorArgs: CustomErrorDeclaration['inputs']) {
+  if (errorArgs.length === 0) {
+    return ''
   }
-  
-  export function generateInterfaceErrorDescription(error: CustomErrorDeclaration): string {
-    return `'${generateErrorSignature(error)}': ErrorFragment;`
-  }
-  
-  export function generateErrorSignature(error: CustomErrorDeclaration): string {
-    return `${error.name}(${error.inputs.map((input: any) => input.type.originalType).join(',')})`
-  }
-  
-  export function generateErrorInputs(errorArgs: CustomErrorDeclaration["inputs"]) {
-    if (errorArgs.length === 0) {
-      return ''
-    }
-    return (
-      errorArgs
-        .map((arg, index) => {
-          return createPositionalIdentifier(arg.name)
-        })
-        .join(', ') + ', '
-    )
-  }
-  
-  export function generateGetError(error: CustomErrorDeclaration, useSignature: boolean): string {
-    return `getError(nameOrSignature: '${
-      useSignature ? generateErrorSignature(error) : error.name
-    }'): ErrorFragment;`
-  }
-  
-  function generateErrorIdentifier(error: CustomErrorDeclaration, { includeArgTypes }: { includeArgTypes?: boolean } = {}) {
-    if (includeArgTypes) {
-      return getSignatureForFn(error) + '_Error'
-    } else {
-      return error.name + 'Error'
-    }
+  return (
+    errorArgs
+      .map((arg) => {
+        return createPositionalIdentifier(arg.name)
+      })
+      .join(', ') + ', '
+  )
+}
+
+export function generateGetError(error: CustomErrorDeclaration, useSignature: boolean): string {
+  return `getError(nameOrSignature: '${useSignature ? generateErrorSignature(error) : error.name}'): ErrorFragment;`
+}
+
+function generateErrorIdentifier(
+  error: CustomErrorDeclaration,
+  { includeArgTypes }: { includeArgTypes?: boolean } = {},
+) {
+  if (includeArgTypes) {
+    return getSignatureForFn(error) + '_Error'
+  } else {
+    return error.name + 'Error'
   }
+}
diff --git a/packages/target-ethers-v5/src/codegen/index.ts b/packages/target-ethers-v5/src/codegen/index.ts
index 0e3c5ff75..8499a1032 100644
--- a/packages/target-ethers-v5/src/codegen/index.ts
+++ b/packages/target-ethers-v5/src/codegen/index.ts
@@ -12,6 +12,7 @@ import {
 } from 'typechain'
 
 import { FACTORY_POSTFIX, STRUCT_INPUT_POSTFIX } from '../common'
+import { generateErrorTypeExports, generateGetError, generateInterfaceErrorDescription } from './errors'
 import {
   EVENT_IMPORTS,
   EVENT_METHOD_OVERRIDES,
@@ -20,11 +21,6 @@ import {
   generateGetEvent,
   generateInterfaceEventDescription,
 } from './events'
-import {
-  generateInterfaceErrorDescription,
-  generateGetError,
-  generateErrorTypeExports
-} from './errors'
 import {
   codegenFunctions,
   generateDecodeFunctionResultOverload,
diff --git a/packages/target-ethers-v5/test/generation.test.ts b/packages/target-ethers-v5/test/generation.test.ts
index 42d2f9154..d12559ae4 100644
--- a/packages/target-ethers-v5/test/generation.test.ts
+++ b/packages/target-ethers-v5/test/generation.test.ts
@@ -17,6 +17,7 @@ describe('Ethers generation edge cases', () => {
     rawName: 'TestContract',
     functions: {},
     events: {},
+    errors: {},
     structs: {},
     constructor: [{ name: 'constructor', inputs: [], outputs: [], stateMutability: 'nonpayable' }],
     path: [],
diff --git a/packages/typechain/test/parser/abiParser.test.ts b/packages/typechain/test/parser/abiParser.test.ts
index 43671f125..5b22d6cf5 100644
--- a/packages/typechain/test/parser/abiParser.test.ts
+++ b/packages/typechain/test/parser/abiParser.test.ts
@@ -374,18 +374,18 @@ describe('parseError', () => {
     const expectedError = {
       inputs: [
         {
-          internalType: "uint256",
-          name: "magic",
-          type: "uint256"
+          internalType: 'uint256',
+          name: 'magic',
+          type: 'uint256',
         },
         {
-          internalType: "address",
-          name: "target",
-          type: "address"
+          internalType: 'address',
+          name: 'target',
+          type: 'address',
         },
       ],
-      "name": "InsufficientBalance",
-      "type": "error"
+      name: 'InsufficientBalance',
+      type: 'error',
     } as RawAbiDefinition
     const parsedError = parseCustomErrorDeclaration(expectedError, () => {})
 
@@ -395,7 +395,7 @@ describe('parseError', () => {
         { name: 'magic', type: { type: 'uinteger', bits: 256, originalType: 'uint256' } },
         { name: 'target', type: { type: 'address', originalType: 'address' } },
       ],
-      documentation: undefined
+      documentation: undefined,
     })
   })
 })

From fc4dfa7f2b467303227cde9e809c2be3d7b18847 Mon Sep 17 00:00:00 2001
From: fredlacs <32464905+fredlacs@users.noreply.github.com>
Date: Sun, 1 May 2022 15:48:49 +0100
Subject: [PATCH 4/5] Fix copy pasta oversight

---
 packages/typechain/src/parser/abiParser.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/typechain/src/parser/abiParser.ts b/packages/typechain/src/parser/abiParser.ts
index bab958c16..6d916eaf9 100644
--- a/packages/typechain/src/parser/abiParser.ts
+++ b/packages/typechain/src/parser/abiParser.ts
@@ -318,7 +318,7 @@ export function parseCustomErrorDeclaration(
   registerStruct: (struct: StructType) => void,
   documentation?: DocumentationResult,
 ): CustomErrorDeclaration {
-  debug(`Parsing function declaration "${abiPiece.name}"`)
+  debug(`Parsing custom error declaration "${abiPiece.name}"`)
   return {
     name: abiPiece.name,
     inputs: abiPiece.inputs.map(parseRawAbiParameter.bind(null, registerStruct)),

From c29ed324ac15d313380cb1beb50a5ee31a69ec5a Mon Sep 17 00:00:00 2001
From: fredlacs <32464905+fredlacs@users.noreply.github.com>
Date: Sun, 1 May 2022 15:51:49 +0100
Subject: [PATCH 5/5] Remove old artifacts

---
 .../types/v0.8.9/CustomError/TestToken.ts     | 40 -------------------
 .../types/v0.8.9/CustomError/index.ts         |  4 --
 2 files changed, 44 deletions(-)
 delete mode 100644 packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
 delete mode 100644 packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts

diff --git a/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts b/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
deleted file mode 100644
index c925f1c15..000000000
--- a/packages/target-web3-v1-test/types/v0.8.9/CustomError/TestToken.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-/* Autogenerated file. Do not edit manually. */
-/* tslint:disable */
-/* eslint-disable */
-
-import type BN from "bn.js";
-import type { ContractOptions } from "web3-eth-contract";
-import type { EventLog } from "web3-core";
-import type { EventEmitter } from "events";
-import type {
-  Callback,
-  PayableTransactionObject,
-  NonPayableTransactionObject,
-  BlockType,
-  ContractEventLog,
-  BaseContract,
-} from "../../types";
-
-export interface EventOptions {
-  filter?: object;
-  fromBlock?: BlockType;
-  topics?: string[];
-}
-
-export interface TestToken extends BaseContract {
-  constructor(
-    jsonInterface: any[],
-    address?: string,
-    options?: ContractOptions
-  ): TestToken;
-  clone(): TestToken;
-  methods: {
-    transfer(
-      to: string,
-      amount: number | string | BN
-    ): NonPayableTransactionObject<void>;
-  };
-  events: {
-    allEvents(options?: EventOptions, cb?: Callback<EventLog>): EventEmitter;
-  };
-}
diff --git a/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts b/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts
deleted file mode 100644
index 14ee95744..000000000
--- a/packages/target-web3-v1-test/types/v0.8.9/CustomError/index.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/* Autogenerated file. Do not edit manually. */
-/* tslint:disable */
-/* eslint-disable */
-export type { TestToken } from "./TestToken";