`serviceWorkerEntry` breaks `mini-css-extract-plugin` in MV3 only

[fregante]

I'm opening this issue to collect some information I find.

Error

Appears in the background worker on load:

Repro

I think the repro so far is:

const MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
  plugins: [
    // This is the order in my config
    new WebExtensionTarget({
      weakRuntimeCheck: true,

      background: {
        // it works with `pageEntry` on MV2
        serviceWorkerEntry: "background",
      }
    }),
    new MiniCssExtractPlugin(),
  ],
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [MiniCssExtractPlugin.loader, "css-loader"],
      },
    ],
  },
};

import './input.css'
console.log('js loaded')

* {
  color: hotpink;
}

Related

First seen in

• https://github.com/awesome-webextension/webpack-target-webextension/pull/42#issuecomment-1912279842