有人帮我看看这是怎么回事

就是点退出登录然后进404页面点跳转回登录页面的按钮就出现这个问题，因为这个bug所有页面都打不开了 ，怎么解决，求解答

 export const getLocal = (key, type) => {
    let index = localStorage.getItem(key)
    console.log(index)
    let item = JSON.parse(index)
    if (String(item) === 'null') {
        item = type
    }
    return item
}

undefined   
vue-router.mjs?f169:3451 
       SyntaxError: "undefined" is not valid JSON
    at JSON.parse ()
    at getLocal (storage.js?9327:21:1)
    at state (user.js?29c6:13:1)
    at setup (pinia.mjs?b318:1196:1)
    at eval (pinia.mjs?b318:1436:1)
    at EffectScope.run (reactivity.esm-bundler.js?89dc:34:1)
    at eval (pinia.mjs?b318:1436:1)
    at EffectScope.run (reactivity.esm-bundler.js?89dc:34:1)
    at createSetupStore (pinia.mjs?b318:1434:1)
    at createOptionsStore (pinia.mjs?b318:1224:1) 

SyntaxError: "undefined" is not valid JSON
这报错很明显了啊
JSON.parse这个方法无法将其转化非JSON.stringify类型的数据。

你这个index没有值 可写成 let item = index ? JSON.parse(index) : ''

undefined 你看你那里输出得这个，还有你肯定那个地方没处理导致这个样子

 export const getLocal = (key, type) => {
    let index = localStorage.getItem(key);
    if(!index) return type; //添加这一行代码
    console.log(index)
    let item = JSON.parse(index);  //index是undefined ，这里是问题所在！
    if (String(item) === 'null') return type;
    return item
}