refactor: resturcture files so that lincensing info can be bundled properly

src/helpers.ts

@@ -0,0 +1,21 @@
+// SPDX-FileCopyrightText: 2021 Johannes Loher
+//
+// SPDX-License-Identifier: MIT
+
+export function getCanvas(): Canvas {
+    if (!(canvas instanceof Canvas) || !canvas.ready) {
+        throw new Error(getGame().i18n.localize("DS4.ErrorCanvasIsNotInitialized"));
+    }
+    return canvas;
+}
+
+export function getGame(): Game {
+    if (!(game instanceof Game)) {
+        throw new Error("Game is not initialized yet."); // Cannot localize this as we would need to access game to do this.
+    }
+    return game;
+}
+
+export function getGameSafe(): Game | undefined {
+    return game instanceof Game ? game : undefined;
+}