Correctly handling status codes with fetch

[corymsmith]

Fixes #4 to properly throw errors

[daffl]

Is the test at https://github.com/feathersjs/feathers-commons/blob/master/src/test/client.js#L76 missing something? I'm wondering why that passed before.

[corymsmith]

Yes it must be, I looked at the tests a bit and tried to set up some failing tests around it so I could make them pass with this fix and couldn't quite sort it so just tested manually :)

[daffl]

Do you have a breaking service/request combination?

[corymsmith]

I was doing a find that was throwing a 500 or 401 error

[ekryski]

Ya I was literally going to ask the same. The way the common tests are written in feathers-commons it's not easy to throw a 404 to test it. Gonna tinker with it a bit. It is kind of an important one to have a test around.

[daffl]

But it is throwing an error at https://github.com/feathersjs/feathers-rest/blob/master/test/client/server.js#L23 and verifying that the client resolves with that error at https://github.com/feathersjs/feathers-commons/blob/master/src/test/client.js#L76. That should at least send a 500 status code.

[ekryski]

I added a test for this and pushed it to master.