The headless_renderer example doesn't generate an image.

## Bevy version

0.15.0

## What you did

I tried running it with this command: `cargo run --features dynamic_linking --features wayland --example headless_renderer`,
then I got the following log:
```
2024-12-13T13:24:55.197351Z INFO bevy_render::renderer: AdapterInfo { name: "AMD Radeon RX 6650 XT (RADV NAVI23)", vendor: 4098, device: 29679, device_type: DiscreteGpu, driver: "radv", driver_info: "Mesa 24.2.7-arch1.1", backend: Vulkan }
2024-12-13T13:24:55.503365Z INFO headless_renderer: Adding CaptureFramePlugin
2024-12-13T13:24:55.735608Z INFO bevy_window::system: No windows are open, exiting
```

## What went wrong

I was not able to acquire the image until I commented out the following code:
```
.set(WindowPlugin {
primary_window: None,
..default()
})
```

## Additional information

This might be a minor bug in an older version. Should I open a PR to fix it?