Unexpected end of JSON input - Offline mode

[steven10172]

When setting json: true if the status code is 0 an error will be thrown due to there being no responseText.

[steven10172]

After looking into this error I noticed that it might be better to throw an error similar to the CORS check when there is a response of XHR.UNSENT. If there was just a check around the JSON.parse there would be no error thrown for a bad request.