Installing ember-fetch breaks source maps for prod builds

[buschtoens]

Demo: https://github.com/buschtoens/ember-fetch-sourcemap-bug

Installing ember-fetch breaks source maps for prod builds (i.e. builds with minification enabled).

During the build, the following warning is emitted:

[WARN] (broccoli-uglify-sourcemap) "ember-fetch.map" referenced in "assets/vendor.js" could not be found

Source map output without ember-fetch:

{"version":3,"sources":["vendor/ember-cli/vendor-prefix.js","vendor/loader/loader.js","vendor/ember-resolver/legacy-shims.js", ...

Source map output with ember-fetch:

{"version":3,"sources":["0"],"names":["window","Ember ...

[buschtoens]

The problem was introduced with v4.0.0.

While warning about deprecations, the source map gets built correctly:

yarn add -D 'ember-fetch@<4' && ember build -prod && head -c 500 ./dist/assets/vendor*.map

[buschtoens]

Which is weird, because according to v3.4.4...v4.0.0 there is no difference between v3.4.5 and v4.0.0. 🤔

[buschtoens]

Oops, it's not v3.4.4...v4.0.0. I was tired yesterday, sorry 😄. Looking for the right version now.

[buschtoens]

It's v4.0.0...v4.0.1.

Works:

yarn add -D ember-fetch@4.0.0 && ember build -prod && head -c 500 ./dist/assets/vendor*.map

Breaks:

yarn add -D ember-fetch@4.0.1 && ember build -prod && head -c 500 ./dist/assets/vendor*.map

Therefore #112 (#111) bricked it. 🙁

[buschtoens]

ember-fetch/index.js

Lines 128 to 130 in d25abf6

	var polyfillTree = concat(new MergeTrees([find(expandedFetchPath), find(expandedAbortcontrollerPath)]), {
	outputFile: 'ember-fetch.js'
	});

broccoli-concat by default creates a source map and injects a sourceMappingURL comment into the file. When the file is eventually concatenated into vendor.js, something goes wrong and the sourceMappingURL is not processed and just stays as it is.

This means that later, when broccoli-uglify-sourcemap (L31) processes vendor.js, it finds the rogue sourceMappingURL comment and tries to load the ember-fetch.map, which of course at that point is not part of the tree anymore.

One possible fix is passing sourceMapConfig: { enabled: false } to broccoli-concat to disable source map generation and thus removing the sourceMappingURL comment.

[buschtoens]

I guess the file ends up here and broccoli-concat itself is probably not aware of source maps when joining files.

So I guess passing sourceMapConfig: { enabled: false } is indeed the correct solution to this problem.

[xg-wang]

@stefanpenner @tchak see comment here broccolijs/broccoli-concat#123 (comment)
Any thoughts about this?

[xg-wang]

Under repo https://github.com/buschtoens/ember-fetch-sourcemap-bug

rm yarn.lock
yarn install
ember b -prod

No more Building[WARN] (broccoli-uglify-sourcemap) "ember-fetch.map" referenced in "assets/vendor.js" could not be found

[mhluska]

So the solution here was to nuke the yarn.lock file? 🤣