Log MySQL errors, without die()

<?php
// Description :  With this modifications, mysql error will be added in a logfile
// the color name if available
// using Prestashop > 1.4.4
class MySQL extends MySQLCore
{
    public function displayMySQLError($query = false)
    {
        if($query)
        {
            $debug = debug_backtrace();
            file_puts_content(_PS_ROOT_DIR_."/log/mysql_err.log",'error from '.print_r($debug[1], true).'<br/>'.$query, FILE_APPEND);
        }
    }
}