Remove concatenation plugin, because it causes errors

Author: Ives van Hoorne

config/webpack.config.js

@@ -259,7 +259,6 @@ if (__DEV__) {
 if (__PROD__) {
   config.plugins = [
     ...config.plugins,
-    new webpack.optimize.ModuleConcatenationPlugin(),
     // Minify the code.
     new webpack.LoaderOptionsPlugin({
       minimize: true,

src/sandbox/eval/js/babel-parser.js

@@ -1,10 +1,10 @@
 // @flow
 import type { Module, Directory } from 'common/types';
 
-import 'babel-plugin-transform-async-to-generator';
-import 'babel-plugin-transform-object-rest-spread';
-import 'babel-plugin-transform-class-properties';
-import 'babel-plugin-transform-decorators-legacy';
+import asyncPlugin from 'babel-plugin-transform-async-to-generator';
+import restSpreadPlugin from 'babel-plugin-transform-object-rest-spread';
+import classPropertiesPlugin from 'babel-plugin-transform-class-properties';
+import decoratorsPlugin from 'babel-plugin-transform-decorators-legacy';
 
 import evalModule from '../';
 import resolveDependency from './dependency-resolver';
@@ -15,10 +15,10 @@ const CUSTOM_BABEL_CONFIG_ENABLED = false;
 const DEFAULT_BABEL_CONFIG = {
   presets: ['es2015', 'react', 'stage-0'],
   plugins: [
-    'transform-decorators-legacy',
-    'transform-async-to-generator',
-    'transform-object-rest-spread',
-    'transform-class-properties',
+    decoratorsPlugin,
+    asyncPlugin,
+    restSpreadPlugin,
+    classPropertiesPlugin,
   ],
   retainLines: true,
 };

src/sandbox/eval/js/index.js

@@ -1,5 +1,4 @@
 // @flow
-
 import { transform } from 'babel-standalone';
 
 import type { Module, Directory } from 'common/types';
@@ -33,7 +32,7 @@ const compileCode = (
     return transform(code, babelConfig).code;
   } catch (e) {
     e.message = e.message.split('\n')[0].replace('unknown', moduleName);
-    throw new Error(e);
+    throw e;
   }
 };