eslint: trailing comma fixes, unused var

webpack/shared.js

@@ -12,7 +12,7 @@ const rules = require('./rules');
 module.exports = {
   entry: Object.assign(
     { application: resolve('app/application.js') },
-    { styles: resolve(join(settings.source_path, 'styles/application.scss')) }
+    { styles: resolve(join(settings.source_path, 'styles/application.scss')) },
   ),
 
   output: {
@@ -54,7 +54,7 @@ module.exports = {
         // temporary fix for https://github.com/ReactTraining/react-router/issues/5576
         // to reduce bundle size
         resource.request = resource.request.replace(/^history/, 'history/es');
-      }
+      },
     ),
     new MiniCssExtractPlugin({
       filename: 'css/[name]-[contenthash:8].css',