newsletters: protect render() against missing user (#19486)

combo/apps/newsletters/models.py

@@ -161,7 +161,7 @@ class NewslettersCell(CellBase):
 
     def render(self, context):
         user = context.get('user')
-        if user.is_authenticated():
+        if user and user.is_authenticated():
             form = NewslettersManageForm(instance=self, user=user)
             context['form'] = form
         return super(NewslettersCell, self).render(context)