### 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)

if (control) {
			if (control->data.mouse_filter != Control::MOUSE_FILTER_IGNORE) {
				control->_call_gui_input(ev);
			}
			if (!control->is_inside_tree() || control->is_set_as_top_level()) {
				break;
			}
			if (gui.key_event_accepted) {
				stopped = true;
				break;
			}
			if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP && is_pointer_event && !(is_scroll_event && control->data.force_pass_scroll_events)) {
				
				stopped = true;
				break;
			}
		}
		if (is_input_handled()) {
			
			break;
		}
		if (ci->is_set_as_top_level()) {
			break;
		}
		ev = ev->xformed_by(ci->get_transform()); 
		ci = ci->get_parent_item();
	}
	return stopped;
}
void Viewport::_gui_call_notification(Control *p_control, int p_what) {