MB-11138: new place for documents errors

Change-Id: I9a81d659be54509341f6f96f4d006fd14e9b7f08
Reviewed-on: http://review.couchbase.org/37432
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>