do_fetch_page() checks in the beginning whether there is a saved query
state already, meaning this is not the first page. If there is not it
checks whether the query is for a singulular partitions or a range scan
to decide whether to enable the stateful queries or not. This check
assumed that there is at least one range in _ranges which will not hold
under some circumstances. Add a check for _ranges being empty.
Fixes: #3564
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <cbe64473f8013967a93ef7b2104c7ca0507afac9.1530610709.git.bdenes@scylladb.com>
59a30f0684