title: MongoError: Unknown modifier $pushAll when I try to push an userId into an Array field in Node.js
body: <p>I'm getting a <code>MongoError: Unknown modifier $pushAl</code> error when I try to push an <code>userId</code> to an Array of likes field:</p>
  
  <p><a href="https://i.stack.imgur.com/QgJ1m.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QgJ1m.png" alt="MongoDB push error"></a></p>