Migrate to webpack 4

webpack.config.base.js

@@ -1,8 +1,17 @@
 /* eslint-disable import/no-commonjs */
 'use strict';
 
+const webpack = require('webpack');
+
 const isProduction = process.env.NODE_ENV === 'production';
 
 module.exports = {
+
+  // Some plugins cause errors on the app, so use few plugins.
+  // https://webpack.js.org/concepts/mode/#mode-production
+  mode: isProduction ? 'none' : 'development',
+  plugins: isProduction ? [
+    new webpack.DefinePlugin({'process.env.NODE_ENV': JSON.stringify('production')}),
+  ] : [],
   devtool: isProduction ? false : '#inline-source-map',
 };