### 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)

List<ObjectID> to_erase;
	for (const KeyValue<ObjectID, uint64_t> &E : physics_2d_mouseover) {
		if (!p_clean_all_frames && E.value == p_frame_reference) {
			continue;
		}
		Object *o = ObjectDB::get_instance(E.key);
		if (o) {
			CollisionObject2D *co = Object::cast_to<CollisionObject2D>(o);
			if (co && co->is_inside_tree()) {
				if (p_clean_all_frames && p_paused_only && co->can_process()) {
					continue;
				}
				co->_mouse_exit();
			}
		}
		to_erase.push_back(E.key);
	}
	while (to_erase.size()) {
		physics_2d_mouseover.erase(to_erase.front()->get());
		to_erase.pop_front();
	}
	
	List<Pair<ObjectID, int>> shapes_to_erase;
	for (KeyValue<Pair<ObjectID, int>, uint64_t> &E : physics_2d_shape_mouseover) {
		if (!p_clean_all_frames && E.value == p_frame_reference) {
			continue;
		}
		Object *o = ObjectDB::get_instance(E.key.first);
		if (o) {
			CollisionObject2D *co = Object::cast_to<CollisionObject2D>(o);