### 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)

SubWindowResize subwindow_resize_mode;
		Rect2i subwindow_resize_from_rect;
		Vector<SubWindow> sub_windows; 
	} gui;
	DefaultCanvasItemTextureFilter default_canvas_item_texture_filter = DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_LINEAR;
	DefaultCanvasItemTextureRepeat default_canvas_item_texture_repeat = DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_DISABLED;
	bool disable_input = false;
	bool _gui_call_input(Control *p_control, const Ref<InputEvent> &p_input);
	void _gui_call_notification(Control *p_control, int p_what);
	void _gui_sort_roots();
	Control *_gui_find_control_at_pos(CanvasItem *p_node, const Point2 &p_global, const Transform2D &p_xform);
	void _gui_input_event(Ref<InputEvent> p_event);
	void _perform_drop(Control *p_control = nullptr, Point2 p_pos = Point2());
	void _gui_cleanup_internal_state(Ref<InputEvent> p_event);
	void _push_unhandled_input_internal(const Ref<InputEvent> &p_event);
	Ref<InputEvent> _make_input_local(const Ref<InputEvent> &ev);
	friend class Control;
	List<Control *>::Element *_gui_add_root_control(Control *p_control);
	void _gui_remove_root_control(List<Control *>::Element *RI);
	String _gui_get_tooltip(Control *p_control, const Vector2 &p_pos, Control **r_tooltip_owner = nullptr);
	void _gui_cancel_tooltip();
	void _gui_show_tooltip();
	void _gui_remove_control(Control *p_control);
	void _gui_hide_control(Control *p_control);
	void _gui_force_drag(Control *p_base, const Variant &p_data, Control *p_control);
	void _gui_set_drag_preview(Control *p_base, Control *p_control);
	Control *_gui_get_drag_preview();
	void _gui_remove_focus_for_window(Node *p_window);
	void _gui_unfocus_control(Control *p_control);
	bool _gui_control_has_focus(const Control *p_control);