Datum:  undefined method `start_at' for nil:NilClass !!(@event.start_at && @event.end_at && @event.start_at.to_date != @event.end_at.to_date) ^^^^^^^^^


EventDrop#description delegated to event.description, but event is nil: EventDrop

Kalender

    undefined method `calendar' for nil:NilClass @calendar_object ||= @calendar || @event.calendar ^^^^^^^^^