fix a bug that could prevent user to selet their payment methods

frontend/src/pages/Users/index.tsx

@@ -36,6 +36,8 @@ export default function Users() {
     const { data: allUsers } = useGetUsers();
 
     const names = useMemo(() => {
+        if (!allUsers)
+            return [];
         return allUsers
             ?.map((user: User) => user.name)
             .filter((season, index, array) => array.indexOf(season) === index);