### Godot version

4.2 eca6f0e

### System information

Windows 10 x64

### Issue description


https://github.com/godotengine/godot/assets/2223172/a2796263-4e2e-4b14-a080-b3ad034cc141



### Steps to reproduce

1. Add SubViewport
2. Add Sprite2D
3. Set spirte's texture to ViewportTexture
4. Create new scene
5. Instance the new scene inside the scene with viewport
6. Make sure both scenes are opened
7. Go to instance scene and save it
8. Go to viewport scene

You will see error spam. Reloading the scene fixes it.

### Minimal reproduction project

[vip.zip](https://github.com/godotengine/godot/files/12292386/vip.zip)

ERR_READ_THREAD_GUARD_V(false);
	return handle_input_locally;
}
void Viewport::set_default_canvas_item_texture_filter(DefaultCanvasItemTextureFilter p_filter) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_filter, DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_MAX);
	if (default_canvas_item_texture_filter == p_filter) {
		return;
	}
	default_canvas_item_texture_filter = p_filter;
	switch (default_canvas_item_texture_filter) {
		case DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_NEAREST:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_filter(viewport, RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST);
			break;
		case DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_LINEAR:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_filter(viewport, RS::CANVAS_ITEM_TEXTURE_FILTER_LINEAR);
			break;
		case DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_LINEAR_WITH_MIPMAPS:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_filter(viewport, RS::CANVAS_ITEM_TEXTURE_FILTER_LINEAR_WITH_MIPMAPS);
			break;
		case DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_NEAREST_WITH_MIPMAPS:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_filter(viewport, RS::CANVAS_ITEM_TEXTURE_FILTER_NEAREST_WITH_MIPMAPS);
			break;
		default: {
		}
	}
}
Viewport::DefaultCanvasItemTextureFilter Viewport::get_default_canvas_item_texture_filter() const {