Ensure we don't receive things from local actors

server/middlewares/validators/activitypub/activity.ts

@@ -15,7 +15,7 @@ async function activityPubValidator (req: express.Request, res: express.Response
 
   const serverActor = await getServerActor()
   const remoteActor = res.locals.signature.actor
-  if (serverActor.id === remoteActor.id) {
+  if (serverActor.id === remoteActor.id || remoteActor.serverId === null) {
     logger.error('Receiving request in INBOX by ourselves!', req.body)
     return res.status(HttpStatusCode.CONFLICT_409)
               .end()