Reproducible test repo for Webpack issue #10022 (stderr not being used to report errors).

This repo uses a custom/dummy "build tool" that mocks what other real build tools do when they wrap Webpack. Known tools to be impacted: Rush, webpacker.

Execute npm run build, and notice the error message is not visible, because Webpack's messages all go to stdout whereas stderr stays empty.

$ npm run build

> [email protected] build /Users/nug/Dev/webpack-nostderr
> node my-build-tool.js

# Build has failed: Error: Command failed: webpack -d

# Error details below:

The error can be seen with npx webpack -d:

Hash: bf39fca7c3adfba85a58
Version: webpack 4.41.2
Time: 77ms
Built at: 2019-11-22 2:24:07 PM
  Asset      Size  Chunks             Chunk Names
main.js  4.21 KiB    main  [emitted]  main
Entrypoint main = main.js
[./src/index.js] 239 bytes {main} [built] [failed] [1 error]

ERROR in ./src/index.js 5:0
Module parse failed: Unexpected token (5:0)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
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But it cannot be extracted by a build tool calling webpack for us, and here lies the issue. In this instance I'd like to see at least this part in stderr:

ERROR in ./src/index.js 5:0
Module parse failed: Unexpected token (5:0)