Bug #69828 Missleading error message if trigger fails

Description:
If a trigger is failing, a missleading message is submitted to the user suggesting the query itself is failing.

How to repeat:
Create two tables:
CREATE TABLE `test1` ( `id` int(11) NOT NULL, `data` int(11) NOT NULL);
CREATE TABLE `test2` ( `id` int(11) NOT NULL, `data` int(11) NOT NULL);
Define erroneous trigger on table 1:

CREATE TRIGGER `test_trigger` BEFORE INSERT ON `test1`
FOR EACH
ROW INSERT INTO `test2` ( `id` , `data` , `more_data` )
VALUES (NEW.`id` , 1);

insert data into table 1:
INSERT INTO `test1`(`id`, `data`) VALUES (1,2);

error msg:
#1136 - Column count doesn't match value count at row 1

This is wrong for the query itself, but for the trigger.

Suggested fix:
Report a hint that the trigger itself is failing.

Thank you for the bug report.

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mysql> CREATE TABLE `test1` ( `id` int(11) NOT NULL, `data` int(11) NOT NULL);
Query OK, 0 rows affected (0.05 sec)

mysql> CREATE TABLE `test2` ( `id` int(11) NOT NULL, `data` int(11) NOT NULL);
Query OK, 0 rows affected (0.03 sec)

mysql> CREATE TRIGGER `test_trigger` BEFORE INSERT ON `test1`
    -> FOR EACH
    -> ROW INSERT INTO `test2` ( `id` , `data` , `more_data` )
    -> VALUES (NEW.`id` , 1);
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO `test1`(`id`, `data`) VALUES (1,2);
ERROR 1136 (21S01): Column count doesn't match value count at row 1
mysql>

small update. Same error on 5.6.x too.
tested with 5.6.24