Make id alphanumeric error message better
Make id alphanumeric error message better

mozilla-services/screenshots,mozilla-services/screenshots,fzzzy/pageshot,mozilla-services/pageshot,fzzzy/pageshot,mozilla-services/screenshots,fzzzy/pageshot,mozilla-services/pageshot,mozilla-services/pageshot,mozilla-services/pageshot,fzzzy/pageshot,mozilla-services/screenshots