Invalid source maps cause file system error hiding true error

[devongovett]

🐛 bug report

If there is a build error, we try to map the error location back to the original source file by following source maps. However, if the file pointed to by the source map doesn't exist (e.g. source map is published to npm but source files are not), then the user gets an unhelpful ENOENT when we try to display the diagnostic.

🤔 Expected Behavior

Ideally we'd fall back to show the original error message without following the source map, but this may not be possible since we remap early (in the JS transformer). Checking if the remapped file actually exists even in non-error cases is likely to have a significant performance impact. Alternatively, we could at least show a message like "run with --no-source-maps" to see the original error message or something.

😯 Current Behavior

Build crashes with an unhelpful error message.

[mischnic]

pointed to by the source map doesn't exist (e.g. source map is published to npm but source files are not)

Another situation where that happens: #8392