npm express package doesn't work using edge in c#

[longlostbro]

public MainWindow()
        {
            InitializeComponent();
            Start().Wait();
        }
        public static async Task Start()
        {
            var createHttpServer = Edge.Func(@"
                var http = require('http');
                var express = require('express');
                var ws = require('ws');
                return function (port, cb) {
                    var server = http.createServer(function (req, res) {
                        res.end('Express:\n'+express+'\n WS:\n'+ws);
                    }).listen(port, cb);
                };
            ");

            await createHttpServer(8080);
            //Console.WriteLine(await new WebClient().DownloadStringTaskAsync("http://localhost:8080"));
        }

The above code throws 'System.AggregateException', but when I remove the require('express'); and replace it with a string it prints out the ws object and the string just fine.

both express and ws are installed, so I'm not sure why it doesn't work.