Fix crash when previewing status cell that doesn't have delegate

Not sure how this is possible, but w/e

Tusker/Views/Status/TimelineStatusCollectionViewCell.swift

@@ -762,7 +762,10 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         return UIContextMenuConfiguration {
             ConversationViewController(for: self.statusID, state: self.statusState.copy(), mastodonController: self.mastodonController)
         } actionProvider: { _ in
-            UIMenu(children: self.delegate!.actionsForStatus(status, source: .view(self)))
+            guard let delegate = self.delegate else {
+                return nil
+            }
+            return UIMenu(children: delegate.actionsForStatus(status, source: .view(self)))
         }
     }