register extensions for development

packages/netlify-cms-core/webpack.config.js

@@ -1,10 +1,26 @@
 const path = require('path');
-const { getConfig, rules } = require('../../scripts/webpack.js');
+const FriendlyErrorsWebpackPlugin = require('friendly-errors-webpack-plugin');
+const { getConfig, rules, plugins } = require('../../scripts/webpack.js');
+
+const isProduction = process.env.NODE_ENV === 'production';
+
+const entry = () => {
+  const defaultEntry = ['./index.js'];
+
+  if (isProduction) {
+    return defaultEntry;
+  }
+
+  return [
+    ...defaultEntry,
+    '../scripts/load-extensions.js',
+  ];
+};
 
 module.exports = {
   ...getConfig(),
   context: path.join(__dirname, 'src'),
-  entry: './index.js',
+  entry: entry(),
   module: {
     rules: [
       ...Object.entries(rules)
@@ -26,5 +42,22 @@ module.exports = {
         use: ['to-string-loader', 'css-loader'],
       },
     ],
-  }
+  },
+  plugins: [
+    ...Object.entries(plugins)
+      .filter(([ key ]) => key !== 'friendlyErrors')
+      .map(([ _, plugin ]) => plugin()),
+    new FriendlyErrorsWebpackPlugin({
+      compilationSuccessInfo: {
+        messages: ['Netlify CMS is now running at http://localhost:8080'],
+      },
+    }),
+  ],
+  devServer: {
+    contentBase: './example',
+    watchContentBase: true,
+    quiet: true,
+    host: 'localhost',
+    port: 8080,
+  },
 };