fix: Anify timeout logic running even when fetch resolved

Summary:

Test Plan:

src/controllers/episodes/anify.ts

@@ -1,3 +1,4 @@
+import { PromiseTimedOutError, promiseTimeout } from "~/libs/promiseTimeout";
 import { sortByProperty } from "~/libs/sortByProperty";
 
 import type { EpisodesResponse } from "./episode";
@@ -11,22 +12,18 @@ export async function getEpisodesFromAnify(
   }
 
   let response: AnifyEpisodesResponse[] | null = null;
-  try {
   const abortController = new AbortController();
-    response = await Promise.race([
+  try {
+    response = await promiseTimeout(
       fetch(`https://api.anify.tv/episodes/${aniListId}`, {
         signal: abortController.signal,
       }).then((res) => res.json<AnifyEpisodesResponse[]>()),
-      // set a limit of 30 seconds
-      new Promise((resolve) => setTimeout(resolve, 30 * 1000)).then(() => {
-        abortController.abort("Loading episodes from Anify timed out");
-        console.error(
-          `Loading episodes from Anify timed out; aniListId: ${aniListId}`,
+      30 * 1000,
     );
-        return null;
-      }),
-    ]);
   } catch (e) {
+    if (e instanceof PromiseTimedOutError) {
+      abortController.abort("Loading episodes from Anify timed out");
+    }
     console.error(
       new Error(
         `Error trying to load episodes from anify; aniListId: ${aniListId}`,

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";
+  }
+}