steps to reproduce error.

• npm install
• npm start
• go to http://localhost:8080/ and observe error
• updated any of the scss modules e.g. common.scss and after webpack-dev-server refreshes error is gone.
• check async/*.chunk.js contents in each case injected in the head tag.

Update issue fixed by adding 'vendor': [ "style-loader/lib/addStyles", "css-loader/lib/css-base", ],