title: How to sort a populated document in find request?
body: <p>I would like to sort a populated Document from the collection i fetch, i get an error requesting it.</p>
  
  <p>Let's admit a Document <code>Group</code> (Group) and 'Member' (Group.Members)</p>
  
  <pre><code>Group
    .find({})
    .populate('Members')
  </code></pre>
  
  <p>Works perfectly, but i would like to sort it so i do this:</p>
  
  <pre><code>Group
    .find({})
    .populate('Members', ['_id', 'name'], null, { sort: [[ 'created_at', 'desc' ]] })
  </code></pre>
  
  <p>I get the error <code>TypeError: Invalid select() argument. Must be a string or object.</code> by adding this...</p>