UglifyJSPlugin breaks alias module (mapbox-gl)

[webpack-bot]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
When building for production, UglifyJSPlugin causes Mapbox to throw an Reference Error: n is not defined. Compiling/building works fine without UglifyJSPlugin.

If the current behavior is a bug, please provide the steps to reproduce.
I am using VueJS with webpack, and load Mapbox via

function resolve (dir) {
  return path.join(__dirname, '..', dir)
}
...
alias: {
      'mapbox-gl': resolve('node_modules/mapbox-gl/dist/mapbox-gl.js'),
      'webworkify': 'webworkify-webpack'
}

because of this incompatibility.
In my vue-file, Mapbox is imported as import mapboxgl from 'mapbox-gl';.

My build configuration:
Base:
https://gist.github.com/henningko/5a76d12a14e485bfc4dd62c2e50ad08e
Production:
https://gist.github.com/henningko/3387f41a55558af60205ea00bbc6b530

What is the expected behavior?
The build should run without Reference Errors produces—or provide a way to leave mapbox-gl untouched.

Please mention other relevant information such as the browser version, Node.js version, webpack version and Operating System.
OS X 10.12.3
Node v7.6
npm 4.4
webpack 2.2.1

Thanks :)

---

This issue was moved from webpack/webpack#4414 by @evilebottnawi. Orginal issue was by @henningko.

[alexander-akait]

Seems issue was solved, but we should add tests to avoid problem in future

[kzc]

mishoo/UglifyJS#2520 (comment)

[michael-ciniawsky]

Especially mishoo/UglifyJS#2520 (comment)