Don't create errors for ignored failed commands

[brianreavis]

Objective

1. Reduce overhead from error handling for ECS commands that intentionally ignore errors, such as try_despawn. These commands currently allocate error objects and pass them to a no-op handler (ignore), which can impact performance when many operations fail.

2. Fix a hang when removing ChildOf components during entity despawning. Excessive logging of these failures can cause significant hangs (I'm noticing around 100ms).

   • Fixes "Entity does not exist" warning triggered by DespawnOnExitState for all child components #19777
   • Fixes Warning: missing IDs in observer_propagation #19753

Solution

• Added a ignore_error method to the HandleError trait to use instead of handle_error_with(ignore). It swallows errors and does not create error objects.
• Replaced remove::<ChildOf> with try_remove::<ChildOf> to suppress expected (?) errors and reduce log noise.

Testing

• I ran these changes on a local project.

[chescock]

As someone who often fails to read documentation, I would probably have expected .handle_error_with(None) to be the same as .handle_error(), but one does "ignore" and the other does "default".

It looks like we always know at compile time whether we want Some or None here. Would it work to make a separate method like fn ignore_error(self) -> impl Command? That might even remove a runtime branch.

(If we do want a runtime switch between the behaviors, then maybe it could be something like enum ErrorHandler { Default, Ignore, Custom(fn(BevyError, ErrorContext)) } so that it can cover handle_error, as well.)

[brianreavis]

Good call! Implemented the former.