What is the expected behavior?

Errors that occur while evaluating values inside DefinePlugin should be reported clearly during compilation, with enough context to identify the failing definition.

What is the motivation or use case for adding/changing the behavior?

When DefinePlugin is misconfigured (for example, passing a raw string instead of a stringified value), the resulting errors are often vague or only appear at runtime. This makes debugging difficult and hurts DX.

How should this be implemented in your opinion?

Catch evaluation errors inside DefinePlugin and surface them as informative WebpackErrors, while ensuring internal recursion flags are always reset.

What does this PR do?

• Wraps parser.evaluate() calls in try/catch/finally blocks
• Replaces generic failures with clear WebpackError messages that include the failing key
• Preserves the original error via error.cause for better stack traces
• Ensures recursion flags are safely reset even when evaluation fails
• Helps catch invalid define values earlier during compilation

Benefits

• Better DX with clear, actionable error messages
• Fail-fast behavior during build instead of runtime
• Improved stability by avoiding stuck recursive states

Screenshot

Are you willing to work on this yourself?

Yes.