Do not use return type of on_exchange_third_party_invite_request.

Author: clokep

synapse/federation/transport/server.py

@@ -620,8 +620,8 @@ class FederationThirdPartyInviteExchangeServlet(BaseFederationServlet):
     PATH = "/exchange_third_party_invite/(?P<room_id>[^/]*)"
 
     async def on_PUT(self, origin, content, query, room_id):
-        content = await self.handler.on_exchange_third_party_invite_request(content)
-        return 200, content
+        await self.handler.on_exchange_third_party_invite_request(content)
+        return 200, {}
 
 
 class FederationClientKeysQueryServlet(BaseFederationServlet):