### 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
label->set_text(p_res->get_name());
	} else {
		label->set_text(p_res->get_class());
	}
	drag_control->add_child(label);
	p_from->set_drag_preview(drag_control); 
	label->set_position(Point2((preview->get_width() - label->get_minimum_size().width) / 2, preview->get_height()));
	Dictionary drag_data;
	drag_data["type"] = "resource";
	drag_data["resource"] = p_res;
	drag_data["from"] = p_from;
	return drag_data;
}
Variant EditorNode::drag_files_and_dirs(const Vector<String> &p_paths, Control *p_from) {
	bool has_folder = false;
	bool has_file = false;
	for (int i = 0; i < p_paths.size(); i++) {
		bool is_folder = p_paths[i].ends_with("/");
		has_folder |= is_folder;
		has_file |= !is_folder;
	}
	int max_rows = 6;
	int num_rows = p_paths.size() > max_rows ? max_rows - 1 : p_paths.size(); 
	VBoxContainer *vbox = memnew(VBoxContainer);
	for (int i = 0; i < num_rows; i++) {
		HBoxContainer *hbox = memnew(HBoxContainer);
		TextureRect *icon = memnew(TextureRect);
		Label *label = memnew(Label);
		if (p_paths[i].ends_with("/")) {
			label->set_text(p_paths[i].substr(0, p_paths[i].length() - 1).get_file());