title: (node:63208) DeprecationWarning: collection.ensureIndex is deprecated. Use createIndexes instead
body: <p>Where is this error coming from? I am not using <code>ensureIndex</code> or <code>createIndex</code> in my Nodejs application anywhere. I am using yarn package manager.</p>
  
  <p>Here is my code in <code>index.js</code></p>
  
  <pre><code>import express from 'express';
  import path from 'path';
  import bodyParser from 'body-parser';
  import mongoose from 'mongoose';
  import Promise from 'bluebird';
  
  dotenv.config();
  mongoose.Promise = Promise;
  mongoose.connect('mongodb://localhost:27017/bookworm', { useNewUrlParser: true });
  
  const app = express();
  </code></pre>