The generated native else branch shouldn't try to parse json

[jappeace]

In my case I had a simple connection issue, but because it attempted to parse that result I coudln't see the error.

else {
        try { res = JSON.parse(xhr.responseText); } catch (e) { onError(e); }
        if (res) onError(res);
      }

should become:

else {
       onError(xhr); // let t he user figure it out
      }