Fixing PHP warning see #5654

main/inc/lib/course.lib.php

@@ -714,13 +714,14 @@ class CourseManager {
                     }
                 } else {
                     $students_in_course = SessionManager::get_users_by_session($session_id, '0');
-
+                    if (is_array($students_in_course)) {
                         foreach($students_in_course as $user_item) {
                             $students_in_courses[$user_item['user_id']] = $user_item['user_id'];
                         }
                     }
                 }
             }
+        }
 
         $students = Tracking :: get_student_followed_by_coach($user_id);
         if (!empty($students_in_courses)) {