我尝试使用 express 和 JWT (JsonWebToken) 创建一个应用程序。它在本地运行，但当我尝试在自己家里的服务器上使用它时，它会出现错误。我花了一个小时的时间尝试寻找解决方案，但没有任何效果。

TypeError: Right-hand side of 'instanceof' is not an object
    at Object.module.exports [as sign] (/home/container/node_modules/jsonwebtoken/sign.js:108:58)
    at server.post (/home/container/server.js:51:9)
    at Layer.handle [as handle_request] (/home/container/node_modules/express/lib/router/layer.js:95:5)
    at next (/home/container/node_modules/express/lib/router/route.js:144:13)
    at Route.dispatch (/home/container/node_modules/express/lib/router/route.js:114:3)
    at Layer.handle [as handle_request] (/home/container/node_modules/express/lib/router/layer.js:95:5)
    at /home/container/node_modules/express/lib/router/index.js:284:15
    at Function.process_params (/home/container/node_modules/express/lib/router/index.js:346:12)
    at next (/home/container/node_modules/express/lib/router/index.js:280:10)
    at /home/container/node_modules/body-parser/lib/read.js:137:5

这真的是一个很简单的应用程序，但我找不到为什么会出现上述错误 ^^

这是我的代码：

const cors = require('cors');
const express = require('express');
const bodyParser = require('body-parser');




const server = express();
const port = 3000 || process.env.PORT;

server.options('*', cors());
server.use(bodyParser.json());
server.use(bodyParser.urlencoded({ extended: false }));

const jwt = require('jsonwebtoken');


 server.listen(port, () => {
    console.log(`Server is running on port ${port}`);
});


const posts = [
    {
        user: 'david',
        title: 'post'
    },
    {
        user: 'bryan',
        title: 'post2'
    }
];



server.get('/posts', authenticateToken, (req, response) => {
 response.json(posts.filter(post => post.user === req.user));
});

server.post('/login', (req, res) => {
    const {username, password} = req.body;
    if(username == null) return res.sendStatus(401);

    jwt.sign(username, 'test', (err, token) => {
        if(err) {
            console.log(err);
            return res.sendStatus(403);
        }
    
        console.log(accessToken);
        res.json({accessToken: accessToken});
    });
 });
  
   


function authenticateToken(req, res, next) {
    const authHeader = req.headers['authorization'];
    const token = authHeader && authHeader.split(' ')[1];

    if(token == null) return res.sendStatus(401);
    jwt.verify(token, 'test', (err, user) => {
        if(err) return res.sendStatus(403);
        req.user = user;
        next();
    });
}

我在任何网站上都找不到解决方案。