### Godot version

4.0.3.stable

### System information

Windows 10/11

### Issue description

I want the player's cursor to change when highlighting pickable Area2Ds; to do this, I have the areas modify the `mouse_default_cursor_shape` property on an external Control when the mouse enters or exits. If another Control appears in front of the Area2D while the mouse is over it, there is a chance that the project will crash.

Nothing prints to the IDE's output on this crash. If running the editor with console, then
```
ERROR: Condition "slot >= slot_max" is true. Returning: nullptr
   at: get_instance (./core/object/object.h:972)
```
will sometimes appear alongside the crash. If it appears, it always appears twice.

When I run a debug build of the editor through WinDbg, WinDbg will catch the following exception:
```
(3b58.2aac): Access violation - code c0000005 (!!! second chance !!!)
godot_windows_editor_x86_64!ObjectDB::get_instance [inlined in godot_windows_editor_x86_64!Viewport::_cleanup_mouseover_colliders+0x6f]:
00007ff6`ac254a1f 488b5310        mov     rdx,qword ptr [rbx+10h] ds:cccccccc`c31c419b=????????????????
```
When using this method, the exception is not random; it always occurs on the first attempt.

### Steps to reproduce

- Open the minimal reproduction project in the editor.
- Run the project.
- Click on the Area2D (you'll want visible collision shapes on).
- A full-screen button will pop up. If the game does not crash at this point, clicking the button will hide it so you can try again. It should crash within a few seconds of mashing.

### Minimal reproduction project

[Crash Test.zip](https://github.com/godotengine/godot/files/12027772/Crash.Test.zip)

return size_allocated;
}
Rect2 Viewport::get_visible_rect() const {
	ERR_READ_THREAD_GUARD_V(Rect2());
	Rect2 r;
	if (size == Size2()) {
		r = Rect2(Point2(), DisplayServer::get_singleton()->window_get_size());
	} else {
		r = Rect2(Point2(), size);
	}
	if (size_2d_override != Size2i()) {
		r.size = size_2d_override;
	}
	return r;
}
void Viewport::canvas_parent_mark_dirty(Node *p_node) {
	ERR_MAIN_THREAD_GUARD;
	bool request_update = gui.canvas_parents_with_dirty_order.is_empty();
	gui.canvas_parents_with_dirty_order.insert(p_node->get_instance_id());
	if (request_update) {
		MessageQueue::get_singleton()->push_callable(callable_mp(this, &Viewport::_process_dirty_canvas_parent_orders));
	}
}
void Viewport::_update_audio_listener_2d() {
	if (AudioServer::get_singleton()) {
		AudioServer::get_singleton()->notify_listener_changed();
	}
}
void Viewport::set_as_audio_listener_2d(bool p_enable) {