MB-9731: Fix crash for STREAM REQ sent to a consumer

Change-Id: I8f5c7468f115f53933de23de97e274f8ca4ab48c
Reviewed-on: http://review.couchbase.org/31056
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>