Node.js 类扩展值[object object]不是构造函数或null

我最近开始学习Node.js.我目前有一个使用Express和FiRestore处理前端请求的后端项目，我正在try 实现类和子类，因为该项目变得越来越大，所以我想对方法进行排序并将它们划分为文件，但由于某些原因，我不能在子类RouteProducts上扩展主类，在本例中是Server.

这就是我到目前为止try 过的:

Index.js:

//Importing subclasses
let RouteProducts = require('./requests/routeProducts.js');

class Server {
    constructor(_app,_db){
        this.app = _app;
        this.db = _db;
        this.initExpress();
        this.start();
    }

    initExpress(){
        this.app.use(express.json());
        this.app.use(cors());
    }

    start(){
        this.app.listen(process.env.PORT, () => console.log("Running on port "+process.env.PORT));
    }
}


module.exports = Server;

//Initializing all classes in order
new Server(express(),config);
new RouteProducts();

RouteProducts.js:

let Server = require('../index.js');
const handleProducts = require('./handleCRUD/handleProducts.js');

class RouteProducts extends Server {
    constructor(_app,_db){
        super(_app,_db);
        this.getAllProducts();
    }

    getAllProducts(){
        _app.get("/read/product/", async (req, res) => {
            await handleProducts.getAllProducts(_db,res);
        });
    }

}

module.exports = RouteProducts;

当我使用npx nodemon index.js运行项目时，我收到以下错误(即使我 comments new RouteProducts();):

class RouteProducts extends Server {
                            ^


TypeError: Class extends value [object Object] is not a constructor or null
    at Object.<anonymous> (C:\Users\Estaniel\Documents\Proyectos\source-shop_back\requests\RouteProducts.js:5:29)
    at Module._compile (node:internal/modules/cjs/loader:1241:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)
    at Module.load (node:internal/modules/cjs/loader:1091:32)
    at Module._load (node:internal/modules/cjs/loader:938:12)
    at Module.require (node:internal/modules/cjs/loader:1115:19)
    at require (node:internal/modules/helpers:130:18)
    at Object.<anonymous> (C:\Users\Estaniel\Documents\Proyectos\source-shop_back\Index.js:10:21)
    at Module._compile (node:internal/modules/cjs/loader:1241:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)

Node.js v20.7.0
[nodemon] app crashed - waiting for file changes before starting...

关于这一点我找了很多，但我找不到有什么问题.我把module.exports = Server改成了module.exports = {Server}，但这不起作用.