index.js

module.exports = (nextConfig = {}) => {
  return Object.assign({}, nextConfig, {
    webpack(config, options) {
      if (!options.defaultLoaders) {
        throw new Error(
          'This plugin is not compatible with Next.js versions below 5.0.0 https://err.sh/next-plugins/upgrade'
        )
      }

      config.module.rules.push({
        test: /\.worker\.js$/,
        loader: 'worker-loader',
        options: nextConfig.workerLoaderOptions || {
          name: 'static/[hash].worker.js',
          publicPath: '/_next/'
        }
      })

      // Overcome webpack referencing `window` in chunks
      config.output.globalObject = `(typeof self !== 'undefined' ? self : this)`

      if (typeof nextConfig.webpack === 'function') {
        return nextConfig.webpack(config, options)
      }

      return config
    }
  })
}