How to Connect the mongo db LearningLocker_v2 using express and xapi with vtc-lrs package

Question

I am new to xapi and i don't know to integrate the mongo db with the usage of express and vtc-lrs package. Here i am use the following link for reference npm package link

My code is:

var express = require('express');
var app = express();
var http = require('http');
const xapi = require('vtc-lrs');
var bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended: true }));

app.use("/xapi", new xapi());
let options = {
lrs: new xapi.LRS(),  
connectionString:"mongodb://remote_url:27017/LearningLocker_V2",
getUser:function(req, res) {
  res.send("Connected Succesfully!");
},
baseUrl: "http://localhost:3000/xapi"
};
app.use("/xapi", new xapi(options) );

When i run this face the following error screenshoot