XMLHTTPRequest returns null in response

[sd-knight]

device: HUAWEI P6-U06
android version: 4.2.2
system version: Emotion os 1.6

reason:

xhr.responseType = 'blob';

when the resonpse is null, Response.json() catch a error.

[Gavin-YYC]

same device
same problem
in other advance devices the response is an Object, but in HUAWEI P6, the response is null.