Fatal error: Uncaught TypeError: sort(): Argument #1 ($array) must be of type array, null given in /var/www/html/students/awilki/work/challenge6.php:3 Stack trace: #0 /var/www/html/students/awilki/work/challenge6.php(3): sort() #1 {main} thrown in /var/www/html/students/awilki/work/challenge6.php on line 3