### 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)

ERR_READ_THREAD_GUARD_V(0);
	return RS::get_singleton()->viewport_get_render_info(viewport, RS::ViewportRenderInfoType(p_type), RS::ViewportRenderInfo(p_info));
}
void Viewport::set_snap_controls_to_pixels(bool p_enable) {
	ERR_MAIN_THREAD_GUARD;
	snap_controls_to_pixels = p_enable;
}
bool Viewport::is_snap_controls_to_pixels_enabled() const {
	ERR_READ_THREAD_GUARD_V(false);
	return snap_controls_to_pixels;
}
void Viewport::set_snap_2d_transforms_to_pixel(bool p_enable) {
	ERR_MAIN_THREAD_GUARD;
	snap_2d_transforms_to_pixel = p_enable;
	RS::get_singleton()->viewport_set_snap_2d_transforms_to_pixel(viewport, snap_2d_transforms_to_pixel);
}
bool Viewport::is_snap_2d_transforms_to_pixel_enabled() const {
	ERR_READ_THREAD_GUARD_V(false);
	return snap_2d_transforms_to_pixel;
}
void Viewport::set_snap_2d_vertices_to_pixel(bool p_enable) {
	ERR_MAIN_THREAD_GUARD;
	snap_2d_vertices_to_pixel = p_enable;
	RS::get_singleton()->viewport_set_snap_2d_vertices_to_pixel(viewport, snap_2d_vertices_to_pixel);
}
bool Viewport::is_snap_2d_vertices_to_pixel_enabled() const {
	ERR_READ_THREAD_GUARD_V(false);
	return snap_2d_vertices_to_pixel;
}
bool Viewport::gui_is_dragging() const {