[Notice] Trying to get property of non-object

GET /home/kalender/ics/announcement-152/20211115T-20211118T

Line 720 in /home/www/56/08/msgswde044/event-calendar/code/Calendar.php

Source

711 			$id = str_replace("announcement-","",$id);
712 			$announcement = true;
713 		}
714 		else {
715 			$announcement = false;
716 		}
717 		if(is_numeric($id) && $oid) {
718 			if(!$feed) { 
719 				$event = DataObject::get_by_id($announcement ? $this->data()->getDateTimeClass() : $this->data()->getEventClass(), $id);
720 				$FILENAME = $announcement ? preg_replace("/[^a-zA-Z0-9s]/", "", $event->Title) : $event->URLSegment;
721 			}
722 			else {
723 				$FILENAME = preg_replace("/[^a-zA-Z0-9s]/", "", urldecode($_REQUEST['title']));
724 			}
725 
726 			$FILENAME .= ".ics";

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