### 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)

#ifndef VIEWPORT_H
#define VIEWPORT_H
#include "scene/main/node.h"
#include "scene/resources/texture.h"
#ifndef _3D_DISABLED
class Camera3D;
class CollisionObject3D;
class AudioListener3D;
class World3D;
#endif 
class AudioListener2D;
class Camera2D;
class CanvasItem;
class CanvasLayer;
class Control;
class Label;