title: Mongoose - always return null instead of an error when no result found?
body: <p>Why mongoose always return null instead of an error when no result found?</p>
  
  <pre><code>Person.findOne({ 'name': 'Ghost' }, function (err, person) {
    console.log(err); // null
    if (err) return handleError(err);
  });
  </code></pre>
  
  <p>The person 'Ghost' does not exist in my db so I am expecting an error but I get null instead. Why? How can get get an error instead?</p>