Creating and running a mroonga function causes various crashes, UBSAN member call on null pointer, UBSAN access within null pointer

CREATE FUNCTION mroonga_escape RETURNS STRING SONAME 'ha_mroonga.so';

Query OK, 0 rows affected (0.04 sec)

select mroonga_escape('10');

ERROR 2013 (HY000): Lost connection to MySQL server during query

select mroonga_escape('10');

ERROR 2006 (HY000): MySQL server has gone away

No connection. Trying to reconnect...

CREATE FUNCTION mroonga_escape RETURNS STRING SONAME 'ha_mroonga.so';

Query OK, 0 rows affected (0.01 sec)

SELECT mroonga_escape("+-<>~*()\"\:");

ERROR 2013 (HY000): Lost connection to MySQL server during query

CREATE FUNCTION mroonga_escape RETURNS STRING   SONAME 'ha_mroonga.so';

ERROR 1041 (HY000): Out of memory.