EntityCaps: Add None check

gajim/common/modules/caps.py

@@ -59,6 +59,9 @@ def _entity_caps(self, _con, _stanza, properties):
         if properties.is_self_presence:
             return
 
+        if properties.entity_caps is None:
+            return
+
         jid = str(properties.jid)
 
         hash_method = properties.entity_caps.hash