webpack.config.js

const { merge } = require('webpack-merge');
const commonConfig = require('./webpack/webpack.common');

module.exports = (env, argv) => {
    if (!argv.mode) {
        throw new Error('You must pass an --mode flag into your build for webpack to work!');
    }

    process.env.BABEL_ENV = argv.mode;
    process.env.NODE_ENV = argv.mode;

    const envConfig = require(`./webpack/webpack.${argv.mode}.js`);

    return merge(commonConfig, envConfig);
};