Cannot read property 'status' of undefined error when there is no network

When there is no network the `_request` function fails, without rejecting the Promise, which makes impossible to catch the error when using a callback.

Even though the component can't be used without the network (#388), I think would be good to handle the case.

The error:

`TypeError: Cannot read property 'status' of undefined`

Start by locating the `_request` function and reproduce the no-network case described in the issue. Check the related context in issue #388, then ensure the failed request rejects its Promise so callback users can catch the error; done means the undefined `status` error is handled instead of escaping.

索引モデルが issue の本文から書いたものです。