Fatal error: Uncaught TypeError: mktime(): Argument #4 ($month) must be of type ?int, string given in /home/uhearts/domains/u-hearts.org/public_html/activityCalendar.php:36 Stack trace: #0 /home/uhearts/domains/u-hearts.org/public_html/activityCalendar.php(36): mktime() #1 {main} thrown in /home/uhearts/domains/u-hearts.org/public_html/activityCalendar.php on line 36