MB-8862 correct error handling for getting default pool
from uninitialized node

Change-Id: I0371fc069e0b0335c4bcb1f5ba77bba42317691f
Reviewed-on: http://review.couchbase.org/28320
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>