rxjs: Observable.ajax error 0

RxJS version: 5.0.0-beta.11

Code to reproduce:

const notService = 1234
Rx.Observable
  .ajax(`http://localhost:${notService}/foo`)
  .subscribe(x => {}, err => console.log('Err:', err.message))
;

Expected behavior: Output: Err: ajax network error

Actual behavior: Output: Err: ajax error 0

Additional information: At the moment if you encounter a network error, the xhr spec requires a response with status 0.

I’d argue that the error message is opaque, and we should look use the text ‘network error’ in place of just ‘status 0’ in the AjaxError.

Thoughts?