Fix metrics to check that socket is defined, because got error about userId.

Thanks to xet7 !

Related https://github.com/wekan/wekan/pull/4728,
related https://github.com/wekan/wekan/pull/4700

server/publications/users.js

@@ -118,6 +118,7 @@ I20221023-09:15:09.602(3)?     at packages/ddp-server/livedata_server.js:1496:18
     Meteor.server.stream_server.open_sockets.forEach(
       (socket) =>
         //console.log('meteor session', socket._meteorSession.userId),
+        socket !== undefined &&
         socket._meteorSession?.userId !== null &&
         Users.update(socket._meteorSession.userId, {
           $set: {