Unbeatable Tic-Tac-Toe

Fatal error: Uncaught Error: Call to a member function getElementsByTagName() on null in /usr/local/www/apache24/data/tictactoe/index.php:47 Stack trace: #0 /usr/local/www/apache24/data/tictactoe/index.php(311): fetch_element('t4902', 'moves') #1 {main} thrown in /usr/local/www/apache24/data/tictactoe/index.php on line 47