### 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)

mm->set_device(InputEvent::DEVICE_ID_INTERNAL);
		mm->set_position(get_mouse_position());
		mm->set_global_position(mm->get_position());
		mm->set_alt_pressed(Input::get_singleton()->is_key_pressed(Key::ALT));
		mm->set_shift_pressed(Input::get_singleton()->is_key_pressed(Key::SHIFT));
		mm->set_ctrl_pressed(Input::get_singleton()->is_key_pressed(Key::CTRL));
		mm->set_meta_pressed(Input::get_singleton()->is_key_pressed(Key::META));
		mm->set_button_mask(Input::get_singleton()->get_mouse_button_mask());
		physics_picking_events.push_back(mm);
	}
	while (physics_picking_events.size()) {
		local_input_handled = false;
		Ref<InputEvent> ev = physics_picking_events.front()->get();
		physics_picking_events.pop_front();
		Vector2 pos;
		bool is_mouse = false;
		Ref<InputEventMouseMotion> mm = ev;
		if (mm.is_valid()) {
			pos = mm->get_position();
			is_mouse = true;
		}
		Ref<InputEventMouseButton> mb = ev;
		if (mb.is_valid()) {
			pos = mb->get_position();
			is_mouse = true;
		}
		Ref<InputEventScreenDrag> sd = ev;
		if (sd.is_valid()) {
			pos = sd->get_position();
		}