### Godot version

4.1 rc3

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

This™
![image](https://github.com/godotengine/godot/assets/2223172/cb33110f-a5b0-400a-951f-3fa425f05714)

It can still happen, but it's more difficult to trigger.

### Steps to reproduce

1. Create a new scene with a Control node
2. Add Theme to the Control
3. Open Theme Editor
4. Clear the `theme` property in Control
5. Save, with Theme Editor opened
6. Restart

### Minimal reproduction project

N/A
Control *dock = nullptr;
	for (int i = 0; i < DOCK_SLOT_MAX; i++) {
		if (p_control->get_parent() == dock_slot[i]) {
			dock = dock_slot[i];
			break;
		}
	}
	ERR_FAIL_COND_MSG(!dock, "Control was not in dock.");
	dock->remove_child(p_control);
	_update_dock_slots_visibility();
}
Variant EditorNode::drag_resource(const Ref<Resource> &p_res, Control *p_from) {
	Control *drag_control = memnew(Control);
	TextureRect *drag_preview = memnew(TextureRect);
	Label *label = memnew(Label);
	Ref<Texture2D> preview;
	{
		
		Ref<ImageTexture> texture = gui_base->get_theme_icon(SNAME("FileBigThumb"), SNAME("EditorIcons"));
		Ref<Image> img = texture->get_image();
		img = img->duplicate();
		img->resize(48, 48); 
		preview = ImageTexture::create_from_image(img);
	}
	drag_preview->set_texture(preview);
	drag_control->add_child(drag_preview);
	if (p_res->get_path().is_resource_file()) {
		label->set_text(p_res->get_path().get_file());
	} else if (!p_res->get_name().is_empty()) {