### 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 (Object::cast_to<InputEventKey>(*p_event) != nullptr || Object::cast_to<InputEventShortcut>(*p_event) != nullptr || Object::cast_to<InputEventJoypadButton>(*p_event) != nullptr) {
		ERR_FAIL_COND(!is_inside_tree());
		get_tree()->_call_input_pause(shortcut_input_group, SceneTree::CALL_INPUT_TYPE_SHORTCUT_INPUT, p_event, this);
	}
	
	if (!is_input_handled() && (Object::cast_to<InputEventKey>(*p_event) != nullptr)) {
		ERR_FAIL_COND(!is_inside_tree());
		get_tree()->_call_input_pause(unhandled_key_input_group, SceneTree::CALL_INPUT_TYPE_UNHANDLED_KEY_INPUT, p_event, this);
	}
	
	if (!is_input_handled()) {
		ERR_FAIL_COND(!is_inside_tree());
		get_tree()->_call_input_pause(unhandled_input_group, SceneTree::CALL_INPUT_TYPE_UNHANDLED_INPUT, p_event, this);
	}
	if (physics_object_picking && !is_input_handled()) {
		if (Input::get_singleton()->get_mouse_mode() != Input::MOUSE_MODE_CAPTURED &&
				(Object::cast_to<InputEventMouse>(*p_event) ||
						Object::cast_to<InputEventScreenDrag>(*p_event) ||
						Object::cast_to<InputEventScreenTouch>(*p_event)
								)) {
			physics_picking_events.push_back(p_event);
			set_input_as_handled();
		}
	}
}
void Viewport::set_physics_object_picking(bool p_enable) {