[scoped-custom-element-registry] : Issue with sourcemaps

[michaelwarren1106]

Description

In a stock, non-ejected, create-react-app scaffolded application, using the @webcomponents/scoped-custom-element-registry polyfill package results in sourcemap warnings during the build step potentially caused by the sourcemaps being malformed?

Example

The warning produce is similar to:

WARNING in ./node_modules/@webcomponents/scoped-custom-element-registry/scoped-custom-element-registry.min.js
Module Warning (from ./node_modules/source-map-loader/dist/cjs.js):
Failed to parse source map from 'C:\<APP DIRECTORY>\node_modules\@webcomponents\scoped-custom-element-registry\scoped-custom-element-registry.min.js.map' file: Error: ENOENT: no such file or directory, open 'C:\<APP DIRECTORY>\node_modules\@webcomponents\scoped-custom-element-registry\scoped-custom-element-registry.min.js.map'

The beginning of the generated sourcemap for the polyfill is:

{"version":3,"sources":[" [synthetic:es6/util/arrayiterator] "," [synthetic:es6/util/makeiterator] "," [synthetic:es6/util/arrayfromiterable] "," [synthetic:es6/util/arrayfromiterator] "," [synthetic:util/objectcreate] "," [synthetic:util/global] "," [synthetic:es6/util/construct] "," [synthetic:es6/util/setprototypeof] ","src/scoped-custom-element-registry.js"," [synthetic:es6/util/inherits] "], ...the rest

Steps to reproduce

1. Create new create-react-app application with Typescript
2. Install and import @webcomponents/scoped-custom-element-registry/
3. run the build step: npm run build

Expected behavior

No warnings are shown

Actual behavior

Warning above is shown

Version

@webcomponents/[email protected]

[bicknellr]

IIRC, those weird bracketed source paths are placed there by Closure to represent its injected polyfills. I was messing around with updating some dependencies a while ago and I believe a newer version of Closure fixed this.

[justinfagnani]

Do we think this is fixed now? I replaced Gulp with a direct call to Closure and noticed that the sourcemaps are slightly different.

[michaelwarren1106]

i haven’t seen an error in a long time, and we’ve dumped create-react-app like the rest of the react world has, so i’d call it good for now and re-open if something else comes up?