Merge pull request #772 from openedx/asheehan-edx/fixing-content-meta…

…data-serializer

fix: fixing serializer when missing ent catalog in context

enterprise_catalog/apps/api/v1/serializers.py

@@ -288,6 +288,10 @@ def _add_course_run_enrollment_urls(self, course_instance, serialized_course_run
         child course run and adds it to the serialized representation of the
         course run record in `serialized_course_runs`.
         """
+        # Early guard in case the context has no catalog
+        if not self.context.get('enterprise_catalog'):
+            return
+
         urls_by_course_run_key = {}
         for course_run in ContentMetadata.get_child_records(course_instance):
             urls_by_course_run_key[course_run.content_key] = \