Fatal error: Uncaught Error: Call to a member function prepare() on null in C:\xampp\htdocs\forum\libraries\Database.php:31 Stack trace: #0 C:\xampp\htdocs\forum\libraries\Topic.php(106): Database->query('select topics.*...') #1 C:\xampp\htdocs\forum\topic.php(65): Topic->getTopic('121') #2 {main} thrown in C:\xampp\htdocs\forum\libraries\Database.php on line 31