fix: Anify timeout logic running even when fetch resolved

Summary:

Test Plan:

src/libs/promiseTimeout.spec.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from "bun:test";
+
+import { PromiseTimedOutError, promiseTimeout } from "./promiseTimeout";
+
+describe("promiseTimeout", () => {
+  it("promise resolves within timeout, returns value", () => {
+    expect(
+      promiseTimeout(
+        wait(1).then(() => 2),
+        2,
+      ),
+    ).resolves.toBe(2);
+  });
+
+  it("promise does not resolve within timeout, throws PromiseTimedOutError", () => {
+    expect(
+      promiseTimeout(
+        wait(2).then(() => 2),
+        1,
+      ),
+    ).rejects.toThrow(PromiseTimedOutError);
+  });
+});
+
+function wait(ms: number) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}

src/libs/promiseTimeout.ts

@@ -0,0 +1,27 @@
+export function promiseTimeout<T>(
+  promise: Promise<T>,
+  timeoutMs: number,
+): Promise<T | null> {
+  let hasPromiseResolved = false;
+
+  return Promise.race([
+    promise.then((value) => {
+      hasPromiseResolved = true;
+      return value;
+    }),
+    new Promise((resolve) => setTimeout(resolve, timeoutMs)).then(() => {
+      if (hasPromiseResolved) {
+        return null;
+      }
+
+      throw new PromiseTimedOutError();
+    }),
+  ]);
+}
+
+export class PromiseTimedOutError extends Error {
+  constructor(message?: string) {
+    super(message ?? "Promise timed out");
+    this.name = "PromiseTimedOutError";
+  }
+}