If you get an error like
$ webpack --progress --config resources/assets/build/webpack.config.js Error: Failed because of a stylelint error. at linter.then (/Users/jasper/code/alarsite/wp-content/themes/alar/node_modules/stylelint-webpack-plugin/lib/run-compilation.js:39:14) error Command failed with exit code 1. info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
And you wonder what the issue is just run the following command
yarn run lint:styles
That will tell you what the issue is.