fix: add fallthrough exception for course overview (#31582)

An issue trying to get a course overview for a deleted course and trying
to write back into the DB had been raising unhandled errors. Catching
other classes of errors to keep this function from breaking. Should just
return None in these cases and log the exception.

openedx/core/djangoapps/content/course_overviews/api.py

@@ -24,7 +24,12 @@ def get_course_overview_or_none(course_id):
         return CourseOverview.get_from_id(course_id)
     except CourseOverview.DoesNotExist:
         log.warning(f"Course overview does not exist for {course_id}")
-        return None
+    except Exception as ex:  # pylint: disable=broad-except
+        # NOTE - Included because some cases (e.g. deleted courses) can throw other
+        # types of errors due to with the cache (see APER-2171 and AU-1000).
+        log.exception(f"Unhandled exception getting course overview for {course_id}: {ex}")
+
+    return None
 
 
 def get_course_overview_or_404(course_id):

openedx/core/djangoapps/content/course_overviews/tests/test_api.py

@@ -45,6 +45,16 @@ class TestCourseOverviewsApi(ModuleStoreTestCase):
         retrieved_course_overview = get_course_overview_or_none(course_run_key)
         assert retrieved_course_overview is None
 
+    @patch('openedx.core.djangoapps.content.course_overviews.api.CourseOverview.get_from_id')
+    def test_get_course_overview_or_none_exception(self, mock_get):
+        """
+        Test for `get_course_overview_or_none` function when an exception is raised.
+        """
+        course_run_key = CourseKey.from_string('course-v1:coping+with+exceptions')
+        mock_get.side_effect = Exception()
+        retrieved_course_overview = get_course_overview_or_none(course_run_key)
+        assert retrieved_course_overview is None
+
     def test_get_course_overview_or_404_success(self):
         """
         Test for `test_get_course_overview_or_404` function when the overview exists.