Source Map Debugger Modal: Special Case Syntax Errors for Debug IDs

Syntax errors will cause debug IDs not to be added because the JS crashes in the evaluation phase, which is before the debug ID snippet on top of the file can run.

The good thing is that if you have a syntax error, you likely don’t even want your code to be source mapped, because you want the actual syntax to be shown, not the original code before transpilation.

I think it would make a lot of sense to explain this to users in the source map debugger modal when we see an error with type "SyntaxError".

Start at the source map debugger modal and trace how errors with type "SyntaxError" are displayed. Confirm the existing error-handling path, then make the modal explain why source mapping is unavailable and why the original syntax is shown; done means the explanation appears for syntax errors without changing other error behavior.

Written by the indexing model from the issue text.