ErrCodeNotAZipFile and ErrCodeFileIsEmpty shared 14001 and 14002 with
ErrCodeAPITokenInvalid and ErrCodeInvalidAPITokenPermission, so clients
mapping codes to messages rendered the api token text for a failed import.
The api token codes are the older ones, so the migration errors move to
14011 and 14012.
BREAKING CHANGE: a failed import now returns 14011 instead of 14001 and
14012 instead of 14002.