Generate source maps.

.gitignore

@@ -3,3 +3,4 @@ vendor
 node_modules
 .php_cs.cache
 public/bundle.js
+*.map

package.json

@@ -15,6 +15,7 @@
     "postcss": "^7.0.14",
     "postcss-loader": "^3.0.0",
     "sass-loader": "^7.1.0",
+    "source-map": "^0.7.3",
     "style-loader": "^0.23.1",
     "webpack": "^4.29.6",
     "webpack-cli": "^3.2.3"

webpack.config.js

@@ -2,6 +2,7 @@ const path = require('path');
 
 module.exports = {
     entry: './src/index.js',
+    devtool: "source-map",
     output: {
         filename: 'bundle.js',
         path: path.resolve(__dirname, 'public')