title: node events.js:136 throw er; Unhandled 'error' event
body: <p>I am getting events.js:136 throw er; Unhandled 'error' event don't know how and why?
  i have reinstalled the nodejs and mongodb as well but throwing same error.</p>
  
  <p><strong>package.json</strong></p>
  
  <pre><code>{
  "name": "bookstore",
  "version": "1.0.0",
  "description": "simple bookstore app",
  "main": "app.js",
  "devDependencies": {},
  "scripts": {
      "test": "echo \"Error: no test specified\" &amp;&amp; exit 1"
  },
  "dependencies": {
      "express": "*",
      "body-parser": "*",
      "mongoose": "*"
  },
  "author": "AveesP",
  "license": "ISC"
  </code></pre>
  
  <p>}</p>
  
  <p><strong>App.js code</strong></p>
  
  <pre><code>var express = require('express');
  var app = express();
  var bodyParser = require('body-parser');
  var mongoose = require('mongoose');
  //connect to mongoose
  mongoose.connect('mongodb://localhost/bookstore');
  var db = mongoose.connection;
  app.get('/', function(req, res) {
     res.send('Hello world!');
  });
  app.listen(3000);
  console.log('Running on port 3000...');
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/qCk4q.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qCk4q.jpg" alt="enter image description here"></a></p>