fix(v10/cloudflare): Keep draining after a synchronous transport error

packages/cloudflare/src/transport.ts

@@ -60,12 +60,16 @@ export class IsolatedPromiseBuffer {
 
     const drainController = new AbortController();
     this.drainSignal = drainController.signal;
-    let tasks: PromiseLike<TransportMakeRequestResponse>[];
-    try {
-      tasks = oldTaskProducers.map(taskProducer => taskProducer());
-    } finally {
-      this.drainSignal = undefined;
-    }
+    const tasks = oldTaskProducers.map(taskProducer => {
+      // A request that throws synchronously, such as a custom `fetch`, must not stop the other requests
+      // or throw into the caller.
+      try {
+        return taskProducer();
+      } catch (error) {
+        return Promise.reject(error);
+      }
+    });
+    this.drainSignal = undefined;
 
     return new Promise(resolve => {
       const timer = setTimeout(() => {

packages/cloudflare/test/transport.test.ts

@@ -1,4 +1,4 @@
-import type { EventEnvelope, EventItem } from '@sentry/core';
+import type { EventEnvelope, EventItem, TransportMakeRequestResponse } from '@sentry/core';
 import { createEnvelope, SENTRY_BUFFER_FULL_ERROR, serializeEnvelope } from '@sentry/core';
 import { afterAll, describe, expect, it, vi } from 'vitest';
 import type { CloudflareTransportOptions } from '../src/transport';
@@ -236,6 +236,22 @@ describe('IsolatedPromiseBuffer', () => {
     expect(task2).toHaveBeenCalled();
   });
 
+  it('runs the other tasks of a drain when one task throws synchronously', async () => {
+    const ipb = new IsolatedPromiseBuffer();
+
+    const task1 = vi.fn((): Promise<TransportMakeRequestResponse> => {
+      throw new Error('foo');
+    });
+    const task2 = vi.fn(() => Promise.resolve({}));
+
+    await ipb.add(task1);
+    await ipb.add(task2);
+
+    await expect(ipb.drain()).resolves.toEqual(true);
+
+    expect(task2).toHaveBeenCalled();
+  });
+
   it('should allow for a custom fetch function to be passed in', async () => {
     const customFetch = vi.fn(async () => {
       return {