MDEV-22075 : Server crashes in wsrep_should_replicate_ddl_iterate upon CREATE VIEW

Fixed incorrect pointer reference when table is not available.

mysql-test/suite/galera/r/galera_create_view.result

+connection node_2;
+connection node_1;
+CREATE OR REPLACE VIEW v AS WITH cte AS ( SELECT 1 ) SELECT * FROM cte;
+DROP VIEW v;

mysql-test/suite/galera/t/galera_create_view.test

+--source include/galera_cluster.inc
+ 
+CREATE OR REPLACE VIEW v AS WITH cte AS ( SELECT 1 ) SELECT * FROM cte;
+ 
+# Cleanup
+DROP VIEW v;

sql/wsrep_mysqld.cc

@@ -1744,7 +1744,8 @@ bool wsrep_should_replicate_ddl_iterate(THD* thd, const TABLE_LIST* table_list)
   {
     for (const TABLE_LIST* it= table_list; it; it= it->next_global)
     {
-      if (!wsrep_should_replicate_ddl(thd, it->table->s->db_type()->db_type))
+      if (it->table &&
+          !wsrep_should_replicate_ddl(thd, it->table->s->db_type()->db_type))
         return false;
     }
   }