fix: close proxy socket on client socket "close" event

Author: DudaGod

lib/http-proxy/passes/ws-incoming.js

@@ -136,6 +136,7 @@ module.exports = {
         proxySocket.end();
       });
 
+      socket.on('close', () => proxySocket.end());
       socket.on('end', () => socket.end());
 
       common.setupSocket(proxySocket);