我有一个运行在Ubuntu Linux 18.04（Bionic）上的Node.JS应用程序，它在Node.JS版本8.11.1上运行良好;没有任何错误。但是当我尝试在10.2.1中运行它时，我在创建的服务器上执行 listen（） 方法的瞬间得到了以下错误：

net.js:1416
        throw new ERR_SERVER_ALREADY_LISTEN();
        ^

    Error [ERR_SERVER_ALREADY_LISTEN]: Listen method has been called more than once without closing.
        at Server.listen (net.js:1416:11)
        at Object.<anonymous> (./web-site/bin/www:56:8)
        at Module._compile (internal/modules/cjs/loader.js:699:14)
        at Object.Module._extensions..js (internal/modules/cjs/loader.js:713:10)
        at Module.load (internal/modules/cjs/loader.js:612:32)
        at tryModuleLoad (internal/modules/cjs/loader.js:551:12)
        at Function.Module._load (internal/modules/cjs/loader.js:543:3)
        at Function.Module.runMain (internal/modules/cjs/loader.js:744:10)
        at startup (internal/bootstrap/node.js:238:19)
        at bootstrapNodeJSCore (internal/bootstrap/node.js:572:3)
    Waiting for the debugger to disconnect...

我检查了三遍，但我只调用了 listen（） 方法一次，此外，如果这真的是问题所在，代码将无法在旧版本的Node.JS中工作。
有谁能想到为什么会发生这种情况，以及我可能如何解决它？
下面是我的 bin/www 文件的代码，这是我运行应用时在调试配置中启动的文件：

#!/usr/bin/env node

/**
 * Web start file that supports SSL and listens for traffic on port 7300.
 */

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('aux:server');

/**
 * Get port from environment and store in Express.  If not, use port 3000.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create the HTTPS server.
 */

var fs = require('fs');
var https = require('https');

// Get the location of the private key and fullchain files for SSL support
//  from the environment.
var privkeyPath = process.env.PRIVKEY_PATH;
var fullchainPath = process.env.FULLCHAIN_PATH;

// Validate them.
if (!fs.existsSync(privkeyPath))
    throw new Error("Invalid private key file path: " + privkeyPath);

if (!fs.existsSync(fullchainPath))
    throw new Error("Invalid fullchain file path: " + fullchainPath);

var options = {
    key: fs.readFileSync(privkeyPath),
    cert: fs.readFileSync(fullchainPath),
    requestCert: true,
    rejectUnauthorized: true
};

var server = https.createServer(options, app).listen(port, function(){
    console.log("Certificate enabled express server listening on port " + port);
});

/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
    var port = parseInt(val, 10);

    if (isNaN(port)) {
        // named pipe
        return val;
    }

    if (port >= 0) {
        // port number
        return port;
    }

    return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
    if (error.syscall !== 'listen') {
        throw error;
    }

    var bind = typeof port === 'string'
        ? 'Pipe ' + port
        : 'Port ' + port;

    // handle specific listen errors with friendly messages
    switch (error.code) {
        case 'EACCES':
            console.error(bind + ' requires elevated privileges');
            process.exit(1);
            break;
        case 'EADDRINUSE':
            console.error(bind + ' is already in use');
            process.exit(1);
            break;
        default:

        throw error;
    }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
    var addr = server.address();
    var bind = typeof addr === 'string'
        ? 'pipe ' + addr
        : 'port ' + addr.port;

    debug('Listening on ' + bind);
}