Handle jsPlugin failures

[wagenet]

Prior to this change, certain JS Plugin failures would just point to Oxlint internals instead of the actual JS error.

[graphite-app]

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[Copilot]

Pull Request Overview

This PR improves error handling for JS Plugin failures by adding proper cleanup and validation logic. Previously, when a JS Plugin failed, internal state would remain corrupted, leading to errors that pointed to Oxlint internals rather than the actual JS error source.

Key Changes:

• Added comprehensive state cleanup in initCompiledVisitor to handle previous compilation failures
• Added input validation in mergeVisitFns to catch invalid data early with clear error messages

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[Copilot]

The error message uses template literal syntax but typeof on an array returns 'object', which isn't very helpful. Consider using Array.isArray() check result or providing the actual value type in a more descriptive way, e.g., Expected visitFns to be an array, but got ${visitFns === null ? 'null' : typeof visitFns}.

Suggested change

	throw new TypeError(`Expected visitFns to be an array, but got ${typeof visitFns}`);
	throw new TypeError(`Expected visitFns to be an array, but got ${visitFns === null ? 'null' : typeof visitFns}`);