AC: Add validation error message when API token is missing
AC: Add validation error message when API token is missing

SpotlightUK/TrackerTracker,paperlesspost/TrackerTracker,fstehle/TrackerTracker,fstehle/TrackerTracker,paperlesspost/TrackerTracker,paperlesspost/TrackerTracker,fstehle/TrackerTracker,SpotlightUK/TrackerTracker,SpotlightUK/TrackerTracker,artsy/TrackerTracker