Fix a few notices

lib/ui/screens/notifications_screen.dart

@@ -199,11 +199,7 @@ class _NotificationTile extends StatelessWidget {
     required this.usersList,
     required this.groupsList,
     required this.onDelete,
-  })  : assert(notification != null),
-        assert(usersList != null),
-        assert(groupsList != null),
-        assert(onDelete != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

lib/ui/screens/other_friends_lists_screen.dart

@@ -19,9 +19,7 @@ class OtherUserFriendsListScreen extends StatefulWidget {
     Key? key,
     required this.userID,
     this.enableAppBar = true,
-  })  : assert(userID != null),
-        assert(enableAppBar != null),
-        super(key: key);
+  })  : super(key: key);
 
   @override
   _OtherUserFriendsListScreenState createState() =>

lib/ui/screens/user_page_screen.dart

@@ -21,8 +21,7 @@ class UserPageScreen extends StatefulWidget {
   final int userID;
 
   const UserPageScreen({Key? key, required this.userID})
-      : assert(userID != null),
-        super(key: key);
+      : super(key: key);
 
   @override
   _UserPageScreenState createState() => _UserPageScreenState();