Fatal error: Uncaught TypeError: mysqli_set_charset(): Argument #1 ($mysql) must be of type mysqli, string given in /var/www/html/mp2/lib/db/Sql.php:59 Stack trace: #0 /var/www/html/mp2/lib/db/Sql.php(59): mysqli_set_charset() #1 /var/www/html/mp2/lib/db/Db.php(12): Sql->__construct() #2 /var/www/html/mp2/index.php(31): Db->__construct() #3 {main} thrown in /var/www/html/mp2/lib/db/Sql.php on line 59