fix(handlers): don't look at resp, just dump it to the error
fix(handlers): don't look at resp, just dump it to the error

Resp might be null in this error handler. Don't try to walk it just
dump it into the error.

Fixes #1

madharjan/discovery.etcd.io,jjamor/coreos-private-discovery-service-src,jjamor/coreos-private-discovery-service-src,coreos/discovery.etcd.io,madharjan/discovery.etcd.io,coreos/discovery.etcd.io,tschuy/discovery.etcd.io,tschuy/discovery.etcd.io