[refactor] Moved 'getElementById' to its own TS file.

utils/uiHelpers/getElementById.ts

@@ -0,0 +1,14 @@
+/**
+ * Returns a reference to the first object with the specified value of the ID or NAME attribute,
+ * throwing an error if it is unable to find it.
+ * @param elementId The HTML ID to retrieve the element by.
+ * @throws {Error} When the 'elementId' cannot be found.
+ */
+export function getElementById(elementId: string) {
+    const el: HTMLElement | null = document.getElementById(elementId);
+    if (el === null) {
+        throw new Error(`Unable to find element with id '${elementId}'`);
+    }
+
+    return el;
+}