TypeError in @ampproject/remapping with esbuild 0.24.2 +

[alan-agius4]

[error] TypeError: Cannot read properties of undefined (reading 'map')
    at originalPositionFor (\node_modules\@ampproject\remapping\dist\remapping.umd.js:77:21)
    at originalPositionFor (\node_modules\@ampproject\remapping\dist\remapping.umd.js:88:16)
    at traceMappings (\node_modules\@ampproject\remapping\dist\remapping.umd.js:56:30)
    at remapping (\node_modules\@ampproject\remapping\dist\remapping.umd.js:196:30)
    at transformWithBabel (\node_modules\@angular\build\src\tools\esbuild\i18n-inliner-worker.js:133:45)
    at async inlineLocale (\node_modules\@angular\build\src\tools\esbuild\i18n-inliner-worker.js:35:20)
    at async \node_modules\piscina\dist\worker.js:144:26

Steps to Reproduce

https://stackblitz.com/edit/stackblitz-starters-xnpd219g?file=index.js

Root Cause

Upon investigation, the issue appears to stem from the upgrade of esbuild from 0.24.0 to 0.24.2.

According to the esbuild changelog, the breaking change was introduced in version 0.24.1, as shown below:

It appears this is an intentional change in esbuild, which may require adjustments in @ampproject/remapping.

Expected Behavior

The application should work seamlessly with esbuild@0.24.2 without encountering a TypeError.

Actual Behavior

The application fails with a TypeError in @ampproject/remapping.

Originally posted by @mattlewis92 in #29465

[meriturva]

I'm so sorry to write here but I just would like to know if the PR will be merged and a new version released in the future.
We have to make a decision about disabling or keep source map enabled on few applications or get stuck on Angular v19.0.
Thanks.

[griest024]

@meriturva I suggest you override the esbuild version as described in this comment. It worked for us.

[meriturva]

@griest024 we have just disabled sourcemap generation as a workaround. Override version is not a feasible solution for all the enterprise projects I follow. On the big one project, we are still on Angular v19.0.

Thanks!

[jridgewell]

The stackblitz is erroring at a different location than the OP's stack trace:

        const source = rootSources[segment[1]];
        traced = originalPositionFor(
          source,
          segment[2],
          segment[3],
          segment.length === 5 ? rootNames[segment[4]] : ''
        );

Here, rootSources (constructed from the map's sources field) is an array of 16 items, segment[1] is 16, so we're doing rootSources[16] and getting undefined. Passing undefined to originalPositionFor will cause an error.

But this isn't remapping's fault, it's invalid for a source map to reference a 17th (index 16) source and only include 16 sources. From the sourcemap spec 9.a.iii.14:

If any of sourceIndex, originalLine, or originalColumn are less than 0, or if sourceIndex is greater than or equal to sources’s size, optionally report an error.

[jridgewell]

Looking at the the esbuild code, what it's calling "null entries" seem to be 1-length mappings:

• https://github.com/evanw/esbuild/blob/b914dd30294346aa15fcc04278f4b4b51b8b43b5/internal/linker/linker.go#L7086
• https://github.com/evanw/esbuild/blob/15d56ca7d2196839c1d13a15fc214d6e81169e30/internal/sourcemap/sourcemap.go#L433-L436
• https://github.com/evanw/esbuild/blob/15d56ca7d2196839c1d13a15fc214d6e81169e30/internal/sourcemap/sourcemap.go#L479-L484

If you scan remapping's codebase (or trace-mapping and gen-mapping), you'll see we already handle 1-length mappings. This isn't a new addition to source maps, just a new build tool producing them (Babel and Closure will too).

• remapping/src/source-map-tree.ts

  Lines 117 to 119 in 395a8e7

  	// 1-length segments only move the current generated column, there's no source information
  	// to gather from it.
  	if (segment.length !== 1) {

• remapping/src/source-map-tree.ts

  Lines 162 to 164 in 395a8e7

  	// 1-length segments only move the current generated column, there's no source information
  	// to gather from it.
  	if (segment.length === 1) return SOURCELESS_MAPPING;

[jridgewell]

I opened evanw/esbuild#4082 to resolve the bug in esbuild. Patching that and using a local build of esbuild, I can correctly generate the angular project from angular/angular-cli#29465.