Fallible systems spamming warning log statements

[Testare]

Bevy version

0.15

[Optional] Relevant system information

Arch Linux

What you did

I'm using the RenderPlugin without the WindowsPlugin (Want to use GPU for a CLI tool)

What went wrong

I'm getting this message spammed in my logs each frame:

2025-01-04T16:55:33.895740Z  WARN bevy_ecs::system::function_system: bevy_ecs::event::reader::EventReader<bevy_window::event::WindowClosing> did not run because it requested inaccessible system parameter Res<Events<WindowClosing>>

According to the news posting, these warnings are supposed to happen only once at most.

Additional information

When I add the window feature and the event for WindowClosing, it changes to WindowResizing, and when I add that, it complains about missing resources for Render's camera_system. I could probably just add the WindowsPlugin or add all these resources, but since I don't actually want to create Windows it seems like a waste.

If I truly want the warnings gone I might create a PR in the future to make bevy_render's bevy_window dependency optional (since it is such a niche case I don't think it would be worth taking the core bevy developers' time), but I wanted to file a bug report since the fallible system warning being repeated ad-nauseum seems to be off spec.

[BenjaminBrienen]

The big question is whether bevy is supposed to support using bevy_render without windowing. This might be better stated as a feature request. I might be wrong, though. Maybe the warning spam can just be fixed.

[Testare]

Yeah, I tried to make it clear that I'm not expecting this weird use case of mine to be imminently supported. That would definitely be a feature request at least, but honestly I expect if I really wanted it I should probably make a PR myself.

However, the fallible system spamming is something that seems like generally undesirable behavior, and so I'm reporting THAT as a bug.