carbon/next.config.js

const Uglify = require('uglifyjs-webpack-plugin')

module.exports = {
  // TODO remove `next.configs.js` when this closes: https://github.com/zeit/next.js/issues/1195
  webpack: function(c, { dev }) {
    if (!dev) {
      c.plugins = c.plugins.filter(plugin => plugin.constructor.name !== 'UglifyJsPlugin')
      c.plugins.push(new Uglify())
    }

    return c
  }
}