It was an error during the SQL command!
MySQL error number: #1064
MySQL error: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '%20this.src%20+'', '3.19.74.29')' at line 1
The SQL command:
INSERT INTO error_page_log (url, ip) VALUES ('http://www.bacsbokod.hu/js/highslide0/'+%20this.src%20+'', '3.19.74.29')

Backtrace:

File Line Class Type Function
/var/www/bacsbokod/data/www/bacsbokod.hu/classes/db.class.php 111 db -> db_error
/var/www/bacsbokod/data/www/bacsbokod.hu/config/config.php 130 db -> query
/var/www/bacsbokod/data/www/bacsbokod.hu/index.php 70 require