### 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)

ClassDB::bind_method(D_METHOD("set_size", "size"), &SubViewport::set_size);
	ClassDB::bind_method(D_METHOD("get_size"), &SubViewport::get_size);
	ClassDB::bind_method(D_METHOD("set_size_2d_override", "size"), &SubViewport::set_size_2d_override);
	ClassDB::bind_method(D_METHOD("get_size_2d_override"), &SubViewport::get_size_2d_override);
	ClassDB::bind_method(D_METHOD("set_size_2d_override_stretch", "enable"), &SubViewport::set_size_2d_override_stretch);
	ClassDB::bind_method(D_METHOD("is_size_2d_override_stretch_enabled"), &SubViewport::is_size_2d_override_stretch_enabled);
	ClassDB::bind_method(D_METHOD("set_update_mode", "mode"), &SubViewport::set_update_mode);
	ClassDB::bind_method(D_METHOD("get_update_mode"), &SubViewport::get_update_mode);
	ClassDB::bind_method(D_METHOD("set_clear_mode", "mode"), &SubViewport::set_clear_mode);
	ClassDB::bind_method(D_METHOD("get_clear_mode"), &SubViewport::get_clear_mode);
	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2I, "size", PROPERTY_HINT_NONE, "suffix:px"), "set_size", "get_size");
	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2I, "size_2d_override", PROPERTY_HINT_NONE, "suffix:px"), "set_size_2d_override", "get_size_2d_override");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "size_2d_override_stretch"), "set_size_2d_override_stretch", "is_size_2d_override_stretch_enabled");
	ADD_GROUP("Render Target", "render_target_");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "render_target_clear_mode", PROPERTY_HINT_ENUM, "Always,Never,Next Frame"), "set_clear_mode", "get_clear_mode");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "render_target_update_mode", PROPERTY_HINT_ENUM, "Disabled,Once,When Visible,When Parent Visible,Always"), "set_update_mode", "get_update_mode");
	BIND_ENUM_CONSTANT(CLEAR_MODE_ALWAYS);
	BIND_ENUM_CONSTANT(CLEAR_MODE_NEVER);
	BIND_ENUM_CONSTANT(CLEAR_MODE_ONCE);
	BIND_ENUM_CONSTANT(UPDATE_DISABLED);
	BIND_ENUM_CONSTANT(UPDATE_ONCE);
	BIND_ENUM_CONSTANT(UPDATE_WHEN_VISIBLE);
	BIND_ENUM_CONSTANT(UPDATE_WHEN_PARENT_VISIBLE);
	BIND_ENUM_CONSTANT(UPDATE_ALWAYS);
}
void SubViewport::_validate_property(PropertyInfo &p_property) const {