### 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)

bool stopped = false;
	Ref<InputEvent> ev = p_input;
	
	bool is_pointer_event = Ref<InputEventMouse>(p_input).is_valid() || Ref<InputEventScreenDrag>(p_input).is_valid() || Ref<InputEventScreenTouch>(p_input).is_valid();
	Ref<InputEventMouseButton> mb = p_input;
	bool is_scroll_event = mb.is_valid() &&
			(mb->get_button_index() == MouseButton::WHEEL_DOWN ||
					mb->get_button_index() == MouseButton::WHEEL_UP ||
					mb->get_button_index() == MouseButton::WHEEL_LEFT ||
					mb->get_button_index() == MouseButton::WHEEL_RIGHT);
	CanvasItem *ci = p_control;
	while (ci) {
		Control *control = Object::cast_to<Control>(ci);