1fdd4ff313
Right now _createScreenshot() returns a tuple that indicates failure when a sender requests a screenshot operation before a previously started operation finished. However that doesn't work for the PickColor() method, as it uses a different return type than the other methods. Address this by returning an error instead, which works in any case; arguably trying to start multiple operations in parallel is an error by the caller more than it is a failed operation anyway. https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1288