This should fix a rare case where the Engine.IO connection was upgraded
to WebSocket while the Socket.IO socket was disconnected, which would
result in the following exception:
> TypeError: Cannot read properties of undefined (reading 'forEach')
> at subscribe (/node_modules/socket.io/dist/uws.js:87:11)
> at Socket.<anonymous> (/node_modules/socket.io/dist/uws.js:28:17)
> at Socket.emit (node:events:402:35)
> at WebSocket.onPacket (/node_modules/engine.io/build/socket.js:214:22)
> at WebSocket.emit (node:events:390:28)
> at WebSocket.onPacket (/node_modules/engine.io/build/transport.js:92:14)
> at WebSocket.onData (/node_modules/engine.io/build/transport.js:101:14)
> at message (/node_modules/engine.io/build/userver.js:56:30)
Related: https://github.com/socketio/socket.io/issues/4443