Also listen for the errors message from workers (it's a standard message apparently)
Also listen for the errors message from workers (it's a standard message apparently)

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