### 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
case RenderingDevice::DeviceType::DEVICE_TYPE_INTEGRATED_GPU:
			device_type_string = "integrated";
			break;
		case RenderingDevice::DeviceType::DEVICE_TYPE_DISCRETE_GPU:
			device_type_string = "dedicated";
			break;
		case RenderingDevice::DeviceType::DEVICE_TYPE_VIRTUAL_GPU:
			device_type_string = "virtual";
			break;
		case RenderingDevice::DeviceType::DEVICE_TYPE_CPU:
			device_type_string = "(software emulation on CPU)";
			break;
		case RenderingDevice::DeviceType::DEVICE_TYPE_OTHER:
		case RenderingDevice::DeviceType::DEVICE_TYPE_MAX:
			break; 
	}
	const Vector<String> video_adapter_driver_info = OS::get_singleton()->get_video_adapter_driver_info();
	const String processor_name = OS::get_singleton()->get_processor_name();
	const int processor_count = OS::get_singleton()->get_processor_count();
	
	if (driver_name == "vulkan") {
		driver_name = "Vulkan";
	} else if (driver_name == "opengl3") {
		driver_name = "GLES3";
	}
	if (rendering_method == "forward_plus") {
		rendering_method = "Forward+";
	} else if (rendering_method == "mobile") {
		rendering_method = "Mobile";
	} else if (rendering_method == "gl_compatibility") {