### 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)

MSAA_DISABLED,
		MSAA_2X,
		MSAA_4X,
		MSAA_8X,
		
		MSAA_MAX
	};
	enum ScreenSpaceAA {
		SCREEN_SPACE_AA_DISABLED,
		SCREEN_SPACE_AA_FXAA,
		SCREEN_SPACE_AA_MAX
	};
	enum RenderInfo {
		RENDER_INFO_OBJECTS_IN_FRAME,
		RENDER_INFO_PRIMITIVES_IN_FRAME,
		RENDER_INFO_DRAW_CALLS_IN_FRAME,
		RENDER_INFO_MAX
	};
	enum RenderInfoType {
		RENDER_INFO_TYPE_VISIBLE,
		RENDER_INFO_TYPE_SHADOW,
		RENDER_INFO_TYPE_MAX
	};
	enum DebugDraw {