Cypress bundling the wrong directories and not responding to webpack configuration

[JJ]

I'm using cypress to test a simple JS file in a web environment. The directory includes a docs/ directory generated by typedoc, which includes a file that makes bundling choke:

@ ./docs/scripts/URI.js 20:52-69
 @ . sync ^\.\/.*$
 @ ./src/index.js
 @ ./cypress/integration/browser_spec.js
 
    at handle (/home/jmerelo/.cache/Cypress/7.4.0/Cypress/resources/app/packages/server/node_modules/@cypress/webpack-preprocessor/dist/index.js:172:23)

The point is not, however, to make the bundle work, but to be able to exclude that directory from bundling, as well as others (like coverage we might want to use. In order to do this, I've dropped this file into cypress/plugins/index.js:

const webpackPreprocessor = require('@cypress/webpack-preprocessor')

const webpackOptions = {
  resolve: {
    extensions: [".js"]
  },
  module: {
    rules: [
      {
        exclude: [/docs/],
      }
    ]
  }
};

const options = {
  webpackOptions
};

module.exports = webpackPreprocessor(options);

That's apparently not working. Apparently, that's not working at all. Debug still says:

cypress:webpack load default options +0ms

Configuration shows that, for instance, extension configuration is not used. So anyone can explain what seems to be the problem here?