MDEV-25684 Crash in THD::find_temporary_table while calling spider_direct_sql UDF without temporary table created

The server crashed when SPIDER_DIRECT_SQL UDF was called with
non-existing temporary table.

The bug has been introduced by 91ffdc8. The commit removed
the check, from THD::open_temporary_table(), which ensure that
the target temporary tables exist.

We can fix the bug by adding the check before the call of
THD::open_temporary_table().

storage/spider/mysql-test/spider/bugfix/r/mdev_25684.result

@@ -0,0 +1,18 @@
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3
+
+MDEV-25684 Crash in THD::find_temporary_table while calling spider_direct_sql UDF without temporary table created
+
+connection master_1;
+SELECT SPIDER_DIRECT_SQL('SELECT * FROM s', 'non_existing_temporary_table', 'srv "s_2_1"');
+ERROR HY000: Temporary table 'test.non_existing_temporary_table' is not found
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_25684.cnf

@@ -0,0 +1,3 @@
+!include include/default_mysqld.cnf
+!include ../my_1_1.cnf
+!include ../my_2_1.cnf

storage/spider/mysql-test/spider/bugfix/t/mdev_25684.test

@@ -0,0 +1,19 @@
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+--echo
+--echo MDEV-25684 Crash in THD::find_temporary_table while calling spider_direct_sql UDF without temporary table created
+--echo
+
+--connection master_1
+--error 12703
+SELECT SPIDER_DIRECT_SQL('SELECT * FROM s', 'non_existing_temporary_table', 'srv "s_2_1"');
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log

storage/spider/spd_sys_table.cc

@@ -3818,6 +3818,10 @@ TABLE *spider_find_temporary_table(
 ) {
   DBUG_ENTER("spider_find_temporary_table");
 #ifdef SPIDER_open_temporary_table
+  if (!thd->has_temporary_tables())
+  {
+    DBUG_RETURN(NULL);
+  }
   if (thd->open_temporary_table(table_list))
   {
     DBUG_RETURN(NULL);