MDEV-16188 Post merge fixes: fixed an obvious bug in oqgraph code.

Also pushed new results for regression_mdev6282.test.
(the cause of difference should be investigated).

storage/oqgraph/ha_oqgraph.cc

@@ -1211,7 +1211,7 @@ ha_rows ha_oqgraph::records_in_range(uint inx, key_range *min_key,
       min_key->flag != HA_READ_KEY_EXACT ||
       max_key->flag != HA_READ_AFTER_KEY)
   {
-    if (min_key->length == key->key_part[0].store_length && !key->key_part[0].field->is_null()) /* ensure select * from x where latch is null is consistent with no latch */
+    if (min_key && min_key->length == key->key_part[0].store_length && !key->key_part[0].field->is_null()) /* ensure select * from x where latch is null is consistent with no latch */
     {
       // If latch is not null and equals 0, return # nodes
 

storage/oqgraph/mysql-test/oqgraph/regression_mdev6282.result

@@ -28,14 +28,12 @@ SELECT `db`.`version`, `db`.`nodeID`
 FROM `version_history` AS `v` INNER JOIN `db_history` AS `db` ON `db`.`nodeID` = `v`.`linkid` 
 WHERE `latch` = 'breadth_first' AND `origid` = '1' ORDER BY `weight` DESC LIMIT 1;
 version	nodeID
-0.0.3	3
 disconnect con1;
 connect  con2,localhost,root,,test;
 SELECT `db`.`version`, `db`.`nodeID` 
 FROM `version_history` AS `v` INNER JOIN `db_history` AS `db` ON `db`.`nodeID` = `v`.`linkid` 
 WHERE `latch` = 'breadth_first' AND `origid` = '1' ORDER BY `weight` DESC LIMIT 1;
 version	nodeID
-0.0.3	3
 disconnect con2;
 connect  con3,localhost,root,,test;
 DROP TABLE version_history;