### 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
if (owner) {
					Ref<SceneState> ss_inst = owner->get_scene_instance_state();
					if (ss_inst.is_valid()) {
						ss_inst->update_instance_resource(p_instance_path, current_packed_scene);
					}
					owner->set_editable_instance(instantiated_node, is_editable);
				}
				
				for (AdditiveNodeEntry additive_node_entry : addition_list) {
					Node *parent_node = instantiated_node->get_node_or_null(additive_node_entry.parent);
					if (!parent_node) {
						parent_node = current_edited_scene;
					}
					parent_node->add_child(additive_node_entry.node);
					parent_node->move_child(additive_node_entry.node, additive_node_entry.index);
					
					if (additive_node_entry.owner == original_node) {
						additive_node_entry.owner = instantiated_node;
					}
					additive_node_entry.node->set_owner(additive_node_entry.owner);
					
					{
						Node2D *node_2d = Object::cast_to<Node2D>(additive_node_entry.node);
						if (node_2d) {
							node_2d->set_transform(additive_node_entry.transform_2d);
						}
						Node3D *node_3d = Object::cast_to<Node3D>(additive_node_entry.node);
						if (node_3d) {
							node_3d->set_transform(additive_node_entry.transform_3d);
						}