Util: Add assertions

util/assertions.ts

@@ -0,0 +1,15 @@
+export function VERIFY(condition: boolean, message?: string): asserts condition is true {
+    if (!condition) throw new Error(`VERIFY: ${message ?? 'Condition was not met.'}`);
+}
+
+export function VERIFY_NOT_REACHED(message?: string): void {
+    if (message !== undefined) throw new Error(`VERIFY_NOT_REACHED: ${message}`);
+
+    throw new Error('VERIFY_NOT_REACHED');
+}
+
+export function TODO(message?: string): void {
+    if (message !== undefined) throw new Error(`TODO: ${message}`);
+
+    throw new Error('TODO');
+}