Webpack Style Loader + CSS Modules bug

This repo is a reproduction of an issue with using CSS Modules and Style Loader.

When using CSS Modules composes, the referenced file gets added as a style twice. Changing the injectType to singletonStyleTag has no effect, the contents are added multiple times.

I've included the built output for using MiniCssExtractPlugin which works fine and only includes the referenced file once.

Running

• npm run dev to run the dev server on port 8080.
• npm run build to build for production, where the issue is not present due to using MiniCssExtractPlugin.