message: fix Server::stats crash in UserProcess.
diff: @@ -2631,7 +2631,10 @@ PHP_METHOD(swoole_server, stats)
  sw_add_assoc_long_ex(return_value, ZEND_STRS("close_count"), SwooleStats->close_count);
  sw_add_assoc_long_ex(return_value, ZEND_STRS("tasking_num"), SwooleStats->tasking_num);
  sw_add_assoc_long_ex(return_value, ZEND_STRS("request_count"), SwooleStats->request_count);
  + if (SwooleWG.worker)
  + {
  sw_add_assoc_long_ex(return_value, ZEND_STRS("worker_request_count"), SwooleWG.worker->request_count);
  + }
  if (SwooleG.task_ipc_mode > SW_TASK_IPC_UNIXSOCK && SwooleGS->task_workers.queue)
  {
  