fix extract_mentions for outgoing payloads

federation/entities/activitypub/entities.py

@@ -123,6 +123,7 @@ class ActivitypubNoteMixin(AttachImagesMixin, CleanContentMixin, PublicMixin, Cr
         """
         super().extract_mentions()
 
+        if getattr(self, 'tag_list', None):
             from federation.entities.activitypub.models import Mention # Circulars
             tag_list = self.tag_list if isinstance(self.tag_list, list) else [self.tag_list]
             for tag in tag_list: