[Notice] Trying to get property of non-object

GET /eversfield-full-calander/ics/announcement-2218/20220308T150000-20220308T160000

Line 716 in /usr/www/users/ujisfr/event_calendar/code/Calendar.php

Source

707 			$id = str_replace("announcement-","",$id);
708 			$announcement = true;
709 		}
710 		else {			
711 			$announcement = false;
712 		}
713 		if(is_numeric($id) && $oid) {
714 			if(!$feed) { 
715 				$event = DataObject::get_by_id($announcement ? $this->data()->getDateTimeClass() : $this->data()->getEventClass(), $id);
716 				$FILENAME = $announcement ? preg_replace("/[^a-zA-Z0-9s]/", "", $event->Title) : $event->URLSegment;
717 			}
718 			else {
719 				$FILENAME = preg_replace("/[^a-zA-Z0-9s]/", "", urldecode($_REQUEST['title']));
720 			}
721 
722 			$FILENAME .= ".ics";

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