Restructure frontend code and instantiate game

src/frontend/game.js

 import Phaser from 'phaser';
+import TestScene from './scenes/test';
 
-function preload ()
-{
-    this.load.image('404', 'http://labs.phaser.io/assets/sprites/phaser3-logo.png')
-}
-function create ()
-{
-    this.add.image(300, 400, '404')
-}
-
-let scene = {
-    preload: preload,
-    create: create
-};
+class Game {
+  constructo() {
+    this.config = {
+      type: Phaser.AUTO,
+      width: 800,
+      height: 600,
+      scene: TestScene
+    };
 
-let config = {
-    type: Phaser.AUTO,
-    width: 800,
-    height: 600,
-    scene: scene
-};
-
-let game = new Phaser.Game(config);
+    this.game = new Phaser.Game(this.config);
+  }
+}
 
-export default game;
+export default Game;

src/frontend/scenes/test.js

+function preload () {
+  this.load.image('404', 'http://labs.phaser.io/assets/sprites/phaser3-logo.png')
+}
+function create () {
+  this.add.image(300, 400, '404')
+}
+
+let TestScene = {
+    preload: preload,
+    create: create
+};
+
+export default TestScene;

src/widget.js

 import WidgetBackend from './backends/widget';
+import Game from './frontend/game';
+
+let game = Game();