Fatal error: Uncaught TypeError: Argument 1 passed to Functions::dateFormat() must be of the type string, null given, called in /app/frontend/pages/publications/specific.php on line 23 and defined in /app/classes/class.functions.php:147 Stack trace: #0 /app/frontend/pages/publications/specific.php(23): Functions::dateFormat(NULL, 'd-fullMonth-Y') #1 /app/frontend/layouts/default.php(100): include('/app/frontend/p...') #2 /app/frontend/index.php(36): require_once('/app/frontend/l...') #3 /app/index.php(2): require_once('/app/frontend/i...') #4 {main} thrown in /app/classes/class.functions.php on line 147