How can I deal with ember-ajax raising an exception inside of a promise?

When I validate on my backend it returns a 400. So I make a request like:

this.get('ajax').request('api/foo/', {
  contentType: 'application/json; charset=utf-8',
  method: 'POST',
  data: JSON.stringify(data)
});

The problem is that ember-ajax will raise an exception from inside a promise. How can I deal with that? The 400 is intentional behavior, not an exception, I don't want to see it in my console and it seems to be braking other parts of my app.