### 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)

ERR_READ_THREAD_GUARD_V(Transform2D());
	Transform2D container_transform;
	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(get_parent());
	if (c) {
		if (c->is_stretch_enabled()) {
			container_transform.scale(Vector2(c->get_stretch_shrink(), c->get_stretch_shrink()));
		}
		container_transform = c->get_viewport()->get_screen_transform_internal(p_absolute_position) * c->get_global_transform_with_canvas() * container_transform;
	} else {
		WARN_PRINT_ONCE("SubViewport is not a child of a SubViewportContainer. get_screen_transform doesn't return the actual screen position.");
	}
	return container_transform * get_final_transform();
}
Transform2D SubViewport::get_popup_base_transform() const {
	ERR_READ_THREAD_GUARD_V(Transform2D());
	if (is_embedding_subwindows()) {
		return Transform2D();
	}
	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(get_parent());
	if (!c) {
		return get_final_transform();
	}
	Transform2D container_transform;
	if (c->is_stretch_enabled()) {
		container_transform.scale(Vector2(c->get_stretch_shrink(), c->get_stretch_shrink()));
	}
	return c->get_screen_transform() * container_transform * get_final_transform();
}
bool SubViewport::is_directly_attached_to_screen() const {