Bug#42364 SHOW ERRORS returns empty resultset after dropping non existent table

additional backport of of bug43138 fix


mysql-test/t/myisam-system.test:
  additional backport of of bug43138 fix
sql/sql_db.cc:
  additional backport of of bug43138 fix

mysql-test/r/trigger_notembedded.result

@@ -180,8 +180,6 @@ NULL	mysqltest_db1	trg5	DELETE	NULL	mysqltest_db1	t1	0	NULL	SET @a = 5	ROW	BEFOR
 DROP USER mysqltest_dfn@localhost;
 DROP USER mysqltest_inv@localhost;
 DROP DATABASE mysqltest_db1;
-Warnings:
-Warning	1454	No definer attribute for trigger 'mysqltest_db1'.'trg1'. The trigger will be activated under the authorization of the invoker, which may have insufficient privileges. Please recreate the trigger.
 DELETE FROM mysql.user WHERE User LIKE 'mysqltest_%';
 DELETE FROM mysql.db WHERE User LIKE 'mysqltest_%';
 DELETE FROM mysql.tables_priv WHERE User LIKE 'mysqltest_%';

mysql-test/t/myisam-system.test

@@ -12,11 +12,11 @@ let $MYSQLD_DATADIR= `select @@datadir`;
 drop table if exists t1;
 create table t1 (a int) engine=myisam;
 --remove_file $MYSQLD_DATADIR/test/t1.MYI
---error 1051,6
+--error ER_BAD_TABLE_ERROR,6
 drop table t1;
 create table t1 (a int) engine=myisam;
 --remove_file $MYSQLD_DATADIR/test/t1.MYD
---error 1105,6,29
+--error ER_BAD_TABLE_ERROR,6,29
 drop table t1;
---error 1051
+--error ER_BAD_TABLE_ERROR
 drop table t1;

sql/sql_db.cc

@@ -907,6 +907,9 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
     remove_db_from_cache(db);
     pthread_mutex_unlock(&LOCK_open);
 
+    Drop_table_error_handler err_handler(thd->get_internal_handler());
+    thd->push_internal_handler(&err_handler);
+
     error= -1;
     /*
       We temporarily disable the binary log while dropping the objects
@@ -939,6 +942,7 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
       error = 0;
       reenable_binlog(thd);
     }
+    thd->pop_internal_handler();
   }
   if (!silent && deleted>=0)
   {