Fix error when parsing ignored files with @babel/eslint-parser

[devfservant]

This PR fixes several parsing errors which occurred in @babel/eslint-parser, in particular when a file was ignored.

Related issue: #13331

Q	A
Fixed Issues?	#13331
Patch: Bug Fix?	❔
Major: Breaking Change?	No
Minor: New Feature?	No
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?	No
License	MIT

Changes

• eslint-parser:
  • Implement fallback when normalizing config
  • Add corresponding test case

cc @JLHwung @nicolo-ribaudo @fedeci

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/46284/

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[nicolo-ribaudo]

I'm trying to better understand why plugins might be not set.

When the config is null because the file is ignored, || parseOptions at

babel/eslint/babel-eslint-parser/src/worker/configuration.cjs

Line 70 in 053f94f

return validateResolvedConfig(config, options) || parseOptions;

should replace it with our default config.

(I'll clone this PR locally and test it, but you might already have an answer 😁)

[nicolo-ribaudo]

Ok, the source of the problem is that, while the result of loadPartialConfig will prevent Babel from resolving config files and ignores again, || parserOptions will still include ignore: ... and an empty plugins list.

A better fix would be to replace || parserOptions with something like || getDefaultConfig(parserOptions), which sets/deletes the necessary properties:

function getDefaultParserOptions(options) {
  return {
    plugins: [],
    ...options,
    babelrc: false,
    configFile: false,
    browserslistConfigFile: false,
    ignore: null,
    only: null
  };
}

[devfservant]

Ok, of course, the best is to determine the root cause of all these errors 👍
I'll try to implement your suggestion!

[nicolo-ribaudo]

@devfservant I noticed that your commits aren't associated to your GitHub account. It doesn't matter for us, but if you want them to be linked to your account you can check https://docs.github.com/en/github/committing-changes-to-your-project/troubleshooting-commits/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[nicolo-ribaudo]

@devfservant I linked your commits both to your email (that you use in Git) and to your GitHub autogenerated email, so that they are linked to your account.