fix: skip errors that occurred on virtual lines - #1226
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Where is the bad source location coming from? This kinda looks like it masks a genuine bug elsewhere. Do you have repro steps? Also, we have tests for this code now, might be worth adding a regression test to cover the fix. |
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@motiz88 If you have a babel plugin which takes an empty file like Then the resolver will throw an error which breaks the formatter because it attempts to read lines that don't exist on-disk. |
Brings the branch up to react/metro main at 0ff28e6. No conflicts; the branch's only difference from main remains the five-line guard in refineDependencyLocation.
This fix has had no test since the PR was opened, which is what the review asked for in 2024. Adds one at the integration level, in `build-errors-test.js`, so it exercises the real transform and resolution path rather than constructing the error directly. `injectImportPastEndOfFileTransformer.js` wraps `@react-native/metro-babel-transformer` and, for one fixture, appends `import './does-not-exist';` parsed with `startLine` one line past the end of the source — which is what a plugin that generates and appends code does. The dependency Metro collects then reports a location with no counterpart in the file on disk, so building the code frame for the resolution error walks off the end of `lines`. Without the guard, the build rejects with `TypeError: Cannot read properties of undefined (reading 'length')` in place of the resolution error. With it, the error survives and the code frame degrades to the lines that do exist. The assertion is deliberately not a snapshot: the resolver's list of candidate paths varies between versions, and what matters here is only that the resolution error survives.
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Summary
If you have a module that has
importstatements generated in the transformer, then it could possibly throw a resolver error on a line that won't exist in the on-disk file. Without this change, the process will throw an unhandled error. Here, we just skip the error improvement step and fallback on the default behavior.