chore: check if mounted before setting state in async function (#2194)

lib/pangea/activity_planner/activity_list_view.dart

@@ -88,9 +88,7 @@ class ActivityListViewState extends State<ActivityListView> {
         },
       );
     } finally {
-      setState(() {
+      if (mounted) setState(() => _isLoading = false);
-        _isLoading = false;
-      });
     }
   }