title: NODEMON -- app crashed - waiting for file changes before starting
body: <p><strong><a href="https://www.youtube.com/watch?v=5yTazHkDR4o" rel="nofollow noreferrer">I'm following this tutorial.</a></strong></p>
  <p>When I run <strong><code>npm run server</code></strong>, as at 13:10 in the video, I get the error:</p>
  <p><strong><code>[nodemon] app crashed - waiting for file changes before starting...</code></strong></p>
  <p>Why does this happen? Is Port 5000 already in use?</p>
  <hr />
  <p>Here's the terminal:</p>
  <pre><code>#########:MERN_SHOPPING_LIST #######$ npm run server
  
  mern_shopping_list@1.0.0 server /Users/MyName/Documents/Web Dev/MERN_SHOPPING_LIST
  nodemon server.js
  [nodemon] 1.18.3
  [nodemon] to restart at any time, enter `rs`
  [nodemon] watching: *.*
  [nodemon] starting `node server.js`
  /Users/MyName/Documents/Web Dev/MERN_SHOPPING_LIST/server.js:1
  (function (exports, require, module, __filename, __dirname) { const express = required('express');
                                                                                ^
  ReferenceError: required is not defined
      at Object.&lt;anonymous&gt; (/Users/MyName/Documents/Web Dev/MERN_SHOPPING_LIST/server.js:1:79)
      at Module._compile (module.js:652:30)
      at Object.Module._extensions..js (module.js:663:10)
      at Module.load (module.js:565:32)
      at tryModuleLoad (module.js:505:12)
      at Function.Module._load (module.js:497:3)
      at Function.Module.runMain (module.js:693:10)
      at startup (bootstrap_node.js:191:16)
      at bootstrap_node.js:612:3
  [nodemon] app crashed - waiting for file changes before starting...
  </code></pre>