### 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_FAIL_NULL(p_control);
	ERR_FAIL_COND(p_control->is_inside_tree());
	ERR_FAIL_COND(p_control->get_parent() != nullptr);
	Control *drag_preview = _gui_get_drag_preview();
	if (drag_preview) {
		memdelete(drag_preview);
	}
	p_control->set_as_top_level(true);
	p_control->set_position(gui.last_mouse_pos);
	p_base->get_root_parent_control()->add_child(p_control); 
	p_control->move_to_front();
	gui.drag_preview_id = p_control->get_instance_id();
}
Control *Viewport::_gui_get_drag_preview() {
	if (gui.drag_preview_id.is_null()) {
		return nullptr;
	} else {
		Control *drag_preview = Object::cast_to<Control>(ObjectDB::get_instance(gui.drag_preview_id));
		if (!drag_preview) {
			ERR_PRINT("Don't free the control set as drag preview.");
			gui.drag_preview_id = ObjectID();
		}
		return drag_preview;
	}
}
void Viewport::_gui_remove_root_control(List<Control *>::Element *RI) {