fixed crash in attributes screen

TimeUse+/Screens/Home/Cells/ParticipantsCell/ParticipantsCell.swift

@@ -42,8 +42,8 @@ class ParticipantsCell: UICollectionViewCell {
         let activity = TemporaryEvent.shared.activities.first { (activity) -> Bool in
             return activity.id == _parent.activity.id
         }
-        if let attribute = activity?.attribute, _parent.temporaryAttribute.partners == nil {
-            selectItem(attribute.partners, titles: titles)
+        if let attribute = activity?.attribute, let title = attribute.partners, _parent.temporaryAttribute.partners == nil {
+            selectItem(title, titles: titles)
         } else if _parent.temporaryAttribute.partners != nil {
             selectItem(_parent.temporaryAttribute.partners, titles: titles)
         } else {