sw-notifications-module/webpack.config.js

const path = require('path');

module.exports = {
  entry: './src/safari-notifications.js',
  output: {
    filename: 'safari-notifications.js',
    path: path.resolve(__dirname, 'dist'),
    library: 'customModule',
    libraryTarget: 'var'
  },
  mode: 'production',
  target: 'webworker',
  resolve: {
    fallback: {
      "crypto": false // This might be needed if some module tries to access node's crypto, which is not available in browsers
    }
  }
};