### Godot version

v4.0 rc6

### System information

Windows 10

### Issue description

When using a ViewportTexture from a SubViewport on a TextureRect, it throws errors after running the scene once and then switching scenes in the editor.
![Pasted image 20230227212626](https://user-images.githubusercontent.com/44676282/221680047-984fa03e-33d1-4856-9a7f-1700b28423cf.png)


### Steps to reproduce

Run the canvas-scene once.
Switch to another scene in the editor.
Switch back to the canvas-scene

### Minimal reproduction project

[ViewportTextureError.zip](https://github.com/godotengine/godot/files/10844099/ViewportTextureError.zip)

friend class Resource;
	friend class ResourceLoader; 
	static Mutex lock;
	static HashMap<String, Resource *> resources;
#ifdef TOOLS_ENABLED
	static HashMap<String, HashMap<String, String>> resource_path_cache; 
	static RWLock path_cache_lock;
#endif 
	friend void unregister_core_types();
	static void clear();
	friend void register_core_types();
public:
	static bool has(const String &p_path);
	static Ref<Resource> get_ref(const String &p_path);
	static void get_cached_resources(List<Ref<Resource>> *p_resources);
	static int get_cached_resource_count();
};
#endif