Follow up 5ce8055

* Added safe check if `mergeitem` script command being used with no items to be merged. Thank @RadianFord

Signed-off-by: Cydh Ramdh <house.bad@gmail.com>

src/map/script.c

@@ -19120,7 +19120,7 @@ BUILDIN_FUNC(countspiritball) {
 */
 BUILDIN_FUNC(mergeitem) {
 	struct map_session_data *sd = script_rid2sd(st);
-	struct item *items;
+	struct item *items = NULL;
 	uint16 i, count = 0;
 	int nameid = 0;
 
@@ -19180,6 +19180,9 @@ BUILDIN_FUNC(mergeitem) {
 		}
 	}
 
+	if (!items) // Nothing todo here
+		return SCRIPT_CMD_SUCCESS;
+
 	// Retrieve the items
 	for (i = 0; i < count; i++) {
 		uint8 flag = 0;