Route with server function as loader that throws `notFound` crashes route on HMR

[ulrichstark]

Which project does this relate to?

Start

Describe the bug

I have a route that declares a server function as loader and a notFoundComponent.
The server function throws notFound().

import { createFileRoute, notFound } from "@tanstack/react-router";
import { createServerFn } from "@tanstack/react-start";

const loaderServerFn = createServerFn().handler(() => {
  throw notFound();
});

export const Route = createFileRoute("/")({
  loader: async () => await loaderServerFn(),
  component: RouteComponent,
  notFoundComponent: NotFoundComponent,
});

function NotFoundComponent() {
  return <span>NotFoundComponent</span>;
}

function RouteComponent() {
  return <span>RouteComponent</span>;
}

It shows NotFoundComponent as expected when initially navigating to it. When saving the file again in VSCode and therefore triggering an hot module replacement event in the browser, the route crashes with following error:

{"isNotFound":true}

Your Example Website or App

https://github.com/ulrichstark/tanstack-repro-isNotFound-on-hmr

Steps to Reproduce the Bug or Issue

git clone https://github.com/ulrichstark/tanstack-repro-isNotFound-on-hmr
cd tanstack-repro-isNotFound-on-hmr
npm i
npx vite

Then go to /src/routes/index.tsx and hit save to trigger hmr.

Expected behavior

NotFoundComponent should still be shown after hmr.

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.134.12

Additional context

Maybe similar to #5322

[coderabbitai]

A summary of the changes CodeRabbit can apply:

• Update packages/router-core/src/router.ts to treat 'notFound' like 'error' in invalidate (change condition to d.status === 'error' || d.status === 'notFound') and add a new test in packages/react-router/tests/router.test.tsx verifying routes throwing notFound() are correctly reset and display notFoundComponent after HMR invalidation.

• Add a new test in packages/react-router/tests/router.test.tsx that verifies a route returning a 404 notFound (via loader) continues to render its notFoundComponent after router.invalidate(), and update packages/router-core/src/router.ts to treat routes with status 'notFound' as invalidatable (include 'notFound' in the condition that resets a route to pending on invalidate).

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