Fix on Presentation category proposed_schedule_transition_time

Change-Id: I9772c0f3d503195485e796b9197697c2b72594b8

 Fix on Presentation category proposed_schedule_transition_time

Change-Id: I8dd539191a73aac92cadc5b7781bd22f52ac14a0

Author: smarcet

app/Models/Foundation/Summit/Factories/PresentationCategoryFactory.php

@@ -71,8 +71,10 @@ public static function populate(PresentationCategory $track, array $data){
         if(isset($data['chair_visible']))
             $track->setChairVisible(boolval($data['chair_visible']));
 
-        if(isset($data['proposed_schedule_transition_time']))
-            $track->setProposedScheduleTransitionTime(intval($data['proposed_schedule_transition_time']));
+        if(array_key_exists('proposed_schedule_transition_time',$data))
+            $track->setProposedScheduleTransitionTime(
+                is_null($data['proposed_schedule_transition_time']) ? null : intval($data['proposed_schedule_transition_time'])
+            );
 
         return $track;
     }