date_format() mixed with if() in a computed column causes server segfault

alter table event add full_event_name text as (concat(

  date_format(event_starts_on, '%Y-%m-%d '),                         

  if(event_starts_on <> event_ends_on, date_format(event_ends_on, 'to %Y-%m-%d '), ''),

  event_location_id, ' ',                                                              

  event_name));