Intermittent FAIL in `/preload/preload-invalid-resources.html`

```
  ▶ OK /preload/preload-invalid-resources.html
  │   ▶ FAIL [expected PASS] Preloading an invalid image (missing) should preload and not re-fetch
  │   │   → assert_equals: /nothing.png expected 1 but got 2
```