code: function _loadWebpackConfig(configFileName) {
    const customWebpackConfigPath = path.join(process.cwd(), configFileName);
  
    let webpackConfig = null;
  
    try {
      webpackConfig = require(customWebpackConfigPath);
    } catch(err) {}
  
    if (!webpackConfig) {
      webpackConfig = require('../config/webpack/webpack.config.js');
    } else {
      console.log('R> loaded custom webpack config: ', customWebpackConfigPath)
    }
  
    return webpackConfig;
  }
docs: Loading either default webpack configs or user provided ones: