Default channel tagline to “” if it’s not there (Fixes #7194)
Default channel tagline to “” if it’s not there (Fixes #7194)

indirectlylit/kolibri,learningequality/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,learningequality/kolibri,learningequality/kolibri,indirectlylit/kolibri,learningequality/kolibri