handle go back events

frontend/src/index.js

 import React, { createContext, useEffect, useState } from "react";
 import { createRoot } from "react-dom/client";
-import { BrowserRouter as Router, Routes, Route, useNavigationType } from "react-router-dom";
+import { BrowserRouter as Router, Routes, Route } from "react-router-dom";
 import useWebSocket from "react-use-websocket";
 import axios from "axios";