Added a missing guard against attribute access on None.

 - Legacy-Id: 17852

Author: levkowetz

ietf/mailtrigger/models.py

@@ -84,7 +84,7 @@ def gather_doc_group_mail_list(self, **kwargs):
         addrs = []
         if 'doc' in kwargs:
             doc=kwargs['doc']
-            if doc.group.features.acts_like_wg:
+            if doc.group and doc.group.features.acts_like_wg:
                 if doc.group.list_email:
                     addrs.append(doc.group.list_email)
         return addrs