fix: chain re-raising exceptions

openedx/core/djangoapps/course_roles/helpers.py

@@ -103,12 +103,12 @@ def get_all_user_permissions_for_a_course(user_id, course_id):
         raise ValueError(_('user_id and course_id must not be None'))
     try:
         user = User.objects.get(pk=user_id)
-    except User.DoesNotExist:
-        raise ValueError(_('user does not exist'))
+    except User.DoesNotExist as exc:
+        raise ValueError(_('user does not exist')) from exc
     try:
         course = modulestore().get_course(course_id)
-    except AssertionError:
-        raise ValueError(_('course_id is not valid'))
+    except AssertionError as exc:
+        raise ValueError(_('course_id is not valid')) from exc
     if not course:
         raise ValueError(_('course does not exist'))
     course_permissions = set(CourseRolesUserRole.objects.filter(

openedx/core/djangoapps/course_roles/views.py

@@ -39,12 +39,12 @@ def get(self, request):
             raise ParseError('Required course_id parameter is missing')
         try:
             course_key = CourseKey.from_string(course_id)
-        except InvalidKeyError:
-            raise ParseError('Invalid course_id parameter')
+        except InvalidKeyError as exc:
+            raise ParseError('Invalid course_id parameter') from exc
         try:
             permissions = {
                 'permissions': get_all_user_permissions_for_a_course(user_id, course_key),
             }
-        except ValueError as e:
-            raise NotFound(str(e))
+        except ValueError as exc:
+            raise NotFound(str(exc)) from exc
         return Response(permissions)