title: Mongoose save() using native promise - how to catch errors
body: <p>I am trying to catch errors thrown from Mongoose using Mongoose's native promises.  But I don't know where to get the error object from Mongoose.</p>
  
  <p>I would like the errors to be thrown in the <code>.then()</code>s and caught in <code>.catch()</code> if possible.</p>
  
  <pre><code>var contact = new aircraftContactModel(postVars.contact);
  contact.save().then(function(){
      var aircraft = new aircraftModel(postVars.aircraft);
      return aircraft.save();
  })
  .then(function(){
      console.log('aircraft saved')
  }).catch(function(){
      // want to handle errors here
  });
  </code></pre>
  
  <p>Trying not to use another library, as .save() returns a promise natively.</p>