polymer-ajax fails silently when json is not valid json

[ojanvafai]

  jsonHandler: function(xhr) {
    var r = xhr.responseText;
    try {
      return JSON.parse(r);
    } catch (x) {
      return r;
    }
  },

I've I have handleAs="json" and the response isn't valid json, then I have a bug. It'd be better if it just broke and logged the error to the console.

As it is, it took me a while to figure out why event.detail.response was a string.

[tjsavage]

Closing, as element has been deprecated in favor of core-ajax