allowing for 0 top level topics

lms/djangoapps/django_comment_client/utils.py

@@ -120,7 +120,7 @@ def initialize_discussion_info(course):
             node[level]["entries"][entry["title"]] = {"id": entry["id"], 
                                                       "sort_key": entry["sort_key"]}
 
-    for topic, entry in course.metadata['discussion_topics'].items():
+    for topic, entry in course.metadata.get('discussion_topics', {}).items():
         category_map['entries'][topic] = {"id": entry["id"],
                                           "sort_key": entry.get("sort_key", topic)}
 

lms/static/coffee/src/discussion/views/new_post_view.coffee

@@ -42,7 +42,6 @@ class @NewPostView extends Backbone.View
         # change and 2) can't set in initialize because the button is hidden
         @maxNameWidth = @dropdownButton.width() * 0.9
 
-
     # Need a fat arrow because hideTopicDropdown is passed as a callback to bind
     hideTopicDropdown: () =>
         @menuOpen = false