EDUCATOR-3 Check for course before using it.

cms/djangoapps/contentstore/proctoring.py

@@ -7,7 +7,7 @@ import logging
 from django.conf import settings
 
 from xmodule.modulestore.django import modulestore
-
+from xmodule.modulestore.exceptions import ItemNotFoundError
 from contentstore.views.helpers import is_item_in_course_tree
 
 from edx_proctoring.api import (
@@ -40,6 +40,9 @@ def register_special_exams(course_key):
         return
 
     course = modulestore().get_course(course_key)
+    if course is None:
+        raise ItemNotFoundError("Course {} does not exist", unicode(course_key))
+
     if not course.enable_proctored_exams and not course.enable_timed_exams:
         # likewise if course does not have these features turned on
         # then quickly exit