local_err must be NULL before calling object_property_set_bool(), so we
must clear it on each iteration. Let's also use more convenient
error_reportf_err().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20230925194040.68592-8-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>