Aborted streaming server function never settles on the client #8729

Which project does this relate to?

Start

Describe the bug

Aborting a streaming server function (an async generator handler) stops the stream, but the client's for await loop never ends or throws. It stays pending forever.

const stream = await streamNumbers({ signal: controller.signal })
for await (const n of stream) { ... }
// after controller.abort(): never reaches here, and never throws

The console logs Stream processing error: AbortError from processFramedResponse in serverFnFetcher. That catch block logs the error but doesn't pass it to the stream the caller is reading.

Complete minimal reproducer

https://github.com/harisonw/start-stream-abort-repro

Steps to Reproduce the Bug

1. npm install && npm run dev
2. Click Start. Numbers stream in.
3. Click Stop.

Expected behavior

After Stop, the for await loop throws an AbortError (or ends), so the status changes. Instead it stays streaming forever.

Platform

• Router / Start Version: @tanstack/react-start 1.169.2, @tanstack/start-client-core 1.170.37
• OS: Linux
• Browser: Chrome
• Browser Version: 155
• Bundler: vite
• Bundler Version: 8.3.4

Additional context

Not the same as #4651, which was about the server not seeing the abort. This one is on the client.

Drafted with AI help, reviewed by me.