preventing `variable not defined` exception when no option available

slixmpp_omemo/__init__.py

@@ -431,6 +431,7 @@ class XEP_0384(BasePlugin):
         disco = await self.xmpp['xep_0030'].get_info(jid.bare)
         publish_options = PUBLISH_OPTIONS_NODE in disco['disco_info'].get_features()
 
+        options = None
         if publish_options:
             options = _make_publish_options_form({
                 'pubsub#persist_items': True,