### 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)

DEBUG_DRAW_DISABLED,
		DEBUG_DRAW_UNSHADED,
		DEBUG_DRAW_LIGHTING,
		DEBUG_DRAW_OVERDRAW,
		DEBUG_DRAW_WIREFRAME,
		DEBUG_DRAW_NORMAL_BUFFER,
		DEBUG_DRAW_VOXEL_GI_ALBEDO,
		DEBUG_DRAW_VOXEL_GI_LIGHTING,
		DEBUG_DRAW_VOXEL_GI_EMISSION,
		DEBUG_DRAW_SHADOW_ATLAS,
		DEBUG_DRAW_DIRECTIONAL_SHADOW_ATLAS,
		DEBUG_DRAW_SCENE_LUMINANCE,
		DEBUG_DRAW_SSAO,
		DEBUG_DRAW_SSIL,
		DEBUG_DRAW_PSSM_SPLITS,
		DEBUG_DRAW_DECAL_ATLAS,
		DEBUG_DRAW_SDFGI,
		DEBUG_DRAW_SDFGI_PROBES,
		DEBUG_DRAW_GI_BUFFER,
		DEBUG_DRAW_DISABLE_LOD,
		DEBUG_DRAW_CLUSTER_OMNI_LIGHTS,
		DEBUG_DRAW_CLUSTER_SPOT_LIGHTS,
		DEBUG_DRAW_CLUSTER_DECALS,
		DEBUG_DRAW_CLUSTER_REFLECTION_PROBES,
		DEBUG_DRAW_OCCLUDERS,
		DEBUG_DRAW_MOTION_VECTORS,
	};
	enum DefaultCanvasItemTextureFilter {