Make module system handle not having a user, and pass a user in when previewing in the cms

cms/djangoapps/contentstore/views.py

@@ -215,6 +215,7 @@ def preview_module_system(request, preview_id, descriptor):
         render_template=render_from_lms,
         debug=True,
         replace_urls=replace_urls,
+        user=request.user,
     )
 
 

common/lib/xmodule/xmodule/x_module.py

@@ -771,7 +771,7 @@ class ModuleSystem(object):
         self.replace_urls = replace_urls
         self.node_path = node_path
         self.anonymous_student_id = anonymous_student_id
-        self.user_is_staff = user.is_staff
+        self.user_is_staff = user is not None and user.is_staff
 
     def get(self, attr):
         '''	provide uniform access to attributes (like etree).'''