[liuyinchu]

A custom value whose toPostgres() returns null or undefined works as a scalar parameter, but throws TypeError: Cannot read properties of null (reading 'replace') when used inside an array.

The parameter-conversion documentation says array items are recursively converted using the same rules. Prepare each element once and emit unquoted SQL NULL when the prepared value is nullish; other values keep their existing escaping.

Regressions cover null/undefined returns, nested arrays, chained custom conversion, exactly-once conversion, and literal NULL, empty-string, zero and false controls.

Validation on Node 24.22.1 / Linux:

• New regression fails against unchanged production code with the expected TypeError.
• Utility suite: 55 passing.
• Complete pg unit suite (make test-unit): 289 passing.
• Affected-file ESLint and git diff --check: pass.

No live PostgreSQL, native libpq, Cloudflare worker, or full-monorepo integration run is claimed. The published patch is byte-for-byte identical to the tested patch on the unchanged upstream base.

Disclosure: Codex implemented and tested this change under the submitting account's authorization.