[edalzell]

Comb builds the +required / -disallowed filters from the user's words without preg_quote, so metachars leak into the pattern. For example:

• on an index with node.js guide and nodeXjs guide, the query guide -node.js drops both because . matches any character
• +c++ compiles as c+ plus a possessive quantifier
• +foo\ makes preg_match() emit No ending delimiter '#' found, which Laravel turns into a 500 for a user-typed search.

The fix is using preg_quote($word, '#') on the words in removeDisallowedMatches().