Fatal error: Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, null given in /home/wm5/mooc/models/course.php:227 Stack trace: #0 /home/wm5/mooc/models/course.php(377): course->getAllCourse() #1 /home/wm5/mooc/course_info.php(206): course->getCourseTreeFamily() #2 {main} thrown in /home/wm5/mooc/models/course.php on line 227