[fetch] Distinguishing between errors (#25)

Since we are rejecting with a TypeError when the Response is type `error` (aka *network error* per spec), what's your suggestion on how to distinguish between **unparseable url**, **broken location header**, **network timeout**, **redirect limit reached**.

Is checking error message the suggested way?

This might be less of a problem on client side, but when implemented on server side, once I allowed custom timeout and maximum redirect count, that error is no longer solely caused by remote resource, it can also be related to request config. This is a concern for debugging and logging purposes.

for server-side implementation, see [node-fetch](https://github.com/bitinn/node-fetch), also related to #20.

---
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/25