### 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)

} else {
							is_tooltip_shown = true; 
						}
					} else {
						_gui_cancel_tooltip();
					}
				}
				if (!is_tooltip_shown && over->can_process()) {
					if (gui.tooltip_timer.is_valid()) {
						gui.tooltip_timer->release_connections();
						gui.tooltip_timer = Ref<SceneTreeTimer>();
					}
					gui.tooltip_control = over;
					gui.tooltip_pos = over->get_screen_transform().xform(pos);
					gui.tooltip_timer = get_tree()->create_timer(gui.tooltip_delay);
					gui.tooltip_timer->set_ignore_time_scale(true);
					gui.tooltip_timer->connect("timeout", callable_mp(this, &Viewport::_gui_show_tooltip));
				}
			}
			mm->set_position(pos);
			Control::CursorShape cursor_shape = Control::CURSOR_ARROW;
			{
				Control *c = over;
				Vector2 cpos = pos;
				while (c) {
					if (!gui.mouse_focus_mask.is_empty() || c->has_point(cpos)) {
						cursor_shape = c->get_cursor_shape(cpos);
					} else {
						cursor_shape = Control::CURSOR_ARROW;
					}