DEFAULT() doesn't behave as documented

Documentation for default function says:

"If the column has no default value, NULL is returned."

https://mariadb.com/kb/en/default/

A test shows that:

1. [snippet 1] If the column has no default and it is NULLable and the table is empty, no row is returned, even if we are also selecting another expression.
2. [snippet 2] If the column has no default value and it's not NULLable, an error is returned.

MariaDB [test]> CREATE OR REPLACE TABLE t (x INT NULL, y INT NOT NULL);

Query OK, 0 rows affected (0.013 sec)

MariaDB [test]> SELECT DEFAULT(x), 1 FROM t;

Empty set (0.001 sec)

This looks like a bug to me.

MariaDB [test]> SELECT @@sql_mode;

+------------+

| @@sql_mode |

+------------+

|            |

+------------+

1 row in set (0.000 sec)

MariaDB [test]> SELECT DEFAULT(y) FROM t;

ERROR 1364 (HY000): Field 'y' doesn't have a default value

This makes sense to me because no default != NULL, but in that case the docs should be adjusted.