refactor: convert to ECMAScript where necessary

Also drop @league-of-foundry-developers/foundry-vtt-types.

src/utils/utils.js

@@ -0,0 +1,61 @@
+// SPDX-FileCopyrightText: 2021 Johannes Loher
+//
+// SPDX-License-Identifier: MIT
+
+/**
+ * Tests if the given `value` is truthy.
+ *
+ * If it is not truthy, an {@link Error} is thrown, which depends on the given `message` parameter:
+ * - If `message` is a string`, it is used to construct a new {@link Error} which then is thrown.
+ * - If `message` is an instance of {@link Error}, it is thrown.
+ * - If `message` is `undefined`, an {@link Error} with a default message is thrown.
+ * @param {unknown} value   The value to check for truthyness
+ * @param {string | Error} [message] An error message to use when the check fails
+ * @returns {asserts value}
+ */
+export function enforce(value, message) {
+    if (!value) {
+        if (!message) {
+            message =
+                getGameSafe()?.i18n.localize("DS4.ErrorUnexpectedError") ??
+                "There was an unexpected error in the Dungeonslayers 4 system. For more details, please take a look at the console (F12).";
+        }
+        throw message instanceof Error ? message : new Error(message);
+    }
+}
+
+/**
+ * A wrapper that returns the canvas, if it is ready.
+ * @throws if the canvas is not ready yet
+ * @returns {Canvas}
+ */
+export function getCanvas() {
+    enforce(canvas instanceof Canvas && canvas.ready, getGame().i18n.localize("DS4.ErrorCanvasIsNotInitialized"));
+    return canvas;
+}
+
+/**
+ * A wrapper that returns the game, if it already exists.
+ * @throws {Error} if the game is not ready yet
+ * @returns {Game}
+ */
+export function getGame() {
+    enforce(game instanceof Game, "Game is not initialized yet.");
+    return game;
+}
+
+/**
+ * A wrapper that returns the game, or `undefined` if it doesn't exist yet
+ * @returns {Game | undefined}
+ */
+export function getGameSafe() {
+    return game instanceof Game ? game : undefined;
+}
+
+/**
+ * A wrapper that returns `ui.notifications`, or `undefined` if it doesn't exist yet
+ * @returns {Notifications | undefined}
+ */
+export function getNotificationsSafe() {
+    return ui.notifications instanceof Notifications ? ui.notifications : undefined;
+}

src/utils/utils.ts

@@ -1,40 +0,0 @@
-// SPDX-FileCopyrightText: 2021 Johannes Loher
-//
-// SPDX-License-Identifier: MIT
-
-/**
- * Tests if the given `value` is truthy.
- *
- * If it is not truthy, an {@link Error} is thrown, which depends on the given `message` parameter:
- * - If `message` is a string`, it is used to construct a new {@link Error} which then is thrown.
- * - If `message` is an instance of {@link Error}, it is thrown.
- * - If `message` is `undefined`, an {@link Error} with a default message is thrown.
- */
-export function enforce(value: unknown, message?: string | Error): asserts value {
-    if (!value) {
-        if (!message) {
-            message =
-                getGameSafe()?.i18n.localize("DS4.ErrorUnexpectedError") ??
-                "There was an unexpected error in the Dungeonslayers 4 system. For more details, please take a look at the console (F12).";
-        }
-        throw message instanceof Error ? message : new Error(message);
-    }
-}
-
-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.");
-    }
-    return game;
-}
-
-export function getGameSafe(): Game | undefined {
-    return game instanceof Game ? game : undefined;
-}