Bug report

I’m running into Error: Content and Map of this Source is not available (only size() is supported) with Angular.

This seems to have been reported in various other places recently: https://stackoverflow.com/questions/70066980/angular-12-content-and-map-of-this-source-is-not-available-only-size-is-suppo

What is the current behavior?

.../node_modules/webpack-sources/lib/SizeOnlySource.js:16
                return new Error(
                       ^

Error: Content and Map of this Source is not available (only size() is supported)
    at SizeOnlySource._error (.../node_modules/webpack-sources/lib/SizeOnlySource.js:16:10)
    at SizeOnlySource.buffer (.../node_modules/webpack-sources/lib/SizeOnlySource.js:30:14)
    at _isSourceEqual (.../node_modules/webpack/lib/util/source.js:21:51)
    at isSourceEqual (.../node_modules/webpack/lib/util/source.js:43:17)
    at Compilation.emitAsset (.../node_modules/webpack/lib/Compilation.js:4155:9)
    at .../node_modules/webpack/lib/Compiler.js:546:28
    at .../node_modules/webpack/lib/Compiler.js:1127:17
    at eval (eval at create (.../node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:13:1)
The terminal process "zsh '-c', 'yarn run start'" terminated with exit code: 1.

If the current behavior is a bug, please provide the steps to reproduce.

I don’t have a clear reproduction, however I was able to add some logs in emitAsset here, which is part of the stack trace: https://github.com/webpack/webpack/blob/14582fc41504595b04f01561ea19d27391d6b9ac/lib/Compilation.js#L4171-L4176

I added:

	emitAsset(file, source, assetInfo = {}) {
		if (this.assets[file]) {
			try {
				!isSourceEqual(this.assets[file], source);
			} catch (err) {
				console.error(file, this.assets[file], source);
				throw err;
			}

The output before the crash is:

fontawesome-webfont.eot SizeOnlySource { _size: 165742 } RawSource {
  _valueIsBuffer: true,
  _value: <Buffer 6e 87 02 00 ac 86 02 00 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 90 01 00 00 00 00 4c 50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... 165692 more bytes>,
  _valueAsBuffer: <Buffer 6e 87 02 00 ac 86 02 00 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 90 01 00 00 00 00 4c 50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... 165692 more bytes>,
  _valueAsString: undefined
}

It always seems to crash on the same eot file. Notice that this.assets[file] for this file is a SizeOnlySource.

What is the expected behavior?

No crash.

Other relevant information: webpack version: 5.60.0 Node.js version: 16.13.0 Operating System: MacOS 11.4 Additional tools: Angular 13.0.1