Stop counting macOS setTypeOfService EINVAL as a test failure (#389)

## Problem

Full-suite runs on macOS sometimes end with one unhandled error,
`setTypeOfService EINVAL`, blamed on `node-target.test.ts`. All tests
pass, but Vitest counts the error, so the run fails.

```
test worker (Node 24, macOS)              vp dev (Vite)
----------------------------              -------------
waitForServer: fetch 127.0.0.1:P   --->   port check: listen 0.0.0.0:P, then close
  handshake done, still queued            close() resets the queued connection (RST)
  'connect' callback runs
  undici 7: socket.setTypeOfService(0)
  setsockopt(IP_TOS) -> EINVAL
  throws inside the event handler
    -> uncaught -> Vitest "1 error" -> run fails
  (the fetch itself rejects with ECONNRESET and waitForServer retries)
```

- Node 24 bundles undici 7. On each new connection it calls
`socket.setTypeOfService()` with no `try/catch`.
- On macOS, `setsockopt(IP_TOS)` returns EINVAL once the peer has reset
the socket. Linux returns 0, and Node ignores the error on Windows.
- Vite checks that the port is free by briefly listening on `0.0.0.0`
and `::`. If the test polls during that moment, its connection gets
reset.
- Upstream: nodejs/undici#5544. It is fixed in
undici 8.8+, but undici 7 (up to 7.30.0, used by Node 24) still has the
bug.

## Fix

Add a root `test.onUnhandledError` filter that drops only errors with
`syscall: 'setTypeOfService'` and `code: 'EINVAL'`. This does the same
thing as the upstream fix: it treats the failed call as best-effort. The
fetch still rejects, so callers see the failure as before. Other
unhandled errors are still reported.

We can remove the filter once Node 24 ships an undici with the fix.

## Testing

| Check | Before | After |
| --- | --- | --- |
| Test that forces a reset (10 runs) | 10/10 runs fail | 0/10 fail, 12
errors dropped |
| `node-target.test.ts` with fast polling to widen the race (25 runs) |
6/25 fail with this exact error | 0/25 fail, 4 errors dropped |
| `node-target.test.ts` as-is: 20 runs idle, 40 under CPU load | 0/60
(race is rare at 200 ms polling) | - |
| Real `vp dev` startup with tight fetch polling (30 starts) | 7
uncaught EINVAL | - |
| Control: built Node server, same polling (30 starts) | 0 | - |
| Unrelated uncaught error | reported | still reported |
| Linux (Docker, Node 24.21.0), reset socket | `setsockopt` returns 0 |
- |
| `vp lint`, `vp fmt --check`, `node-target.test.ts` | - | pass |
| `vp test run` (full suite, macOS) | - | pass: 688 files passed, 1
skipped; 13062 tests passed, 29 skipped |

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: Brooooooklyn

vite.config.ts

@@ -399,6 +399,15 @@ export default defineConfig({
     fsModuleCache: true,
     silent: 'passed-only',
     sequence: { sequencer: SuiteSequencer },
+    // Node 24 bundles undici 7. Its fetch() calls socket.setTypeOfService() on each new
+    // connection and does not catch errors. On macOS this throws EINVAL when the server has
+    // already reset the connection, e.g. when a test polls a port while Vite briefly binds it
+    // to check that it is free. The fetch still rejects and the caller sees that; only this
+    // stray uncaught copy is dropped. undici 8.8+ ignores the error itself.
+    onUnhandledError(error) {
+      const { code, syscall } = error as { code?: unknown; syscall?: unknown };
+      return !(syscall === 'setTypeOfService' && code === 'EINVAL');
+    },
     projects: [
       {
         extends: false,