websocket 服务器启动如果三天内未触发握手，再次进行调用send方法失败。。用的是c#的fleck。详细错误信息：2021-10-28 11:50:59:websocket错误异常：未将对象引用设置到对象的实例。目前在线数量为：0;详情错误信息：无
发送代码方法如下：
public static void Send(string groupName, string groupValue, string res)
{

        int cc = 0;
        try
        {
            LogHelper.InputLog("步骤1");
            var sockets = allSockets.Where(x => x.GroupName == groupName && x.GroupValue == groupValue);
            if (sockets == null || sockets.Count() <= 0)
            {
                LogHelper.InputLog("步骤4");
            }

            LogHelper.InputLog("步骤2");
            cc = sockets.Count();
            if (cc > 0)
            {
                LogHelper.InputLog("步骤3");
                foreach (var item in sockets.ToList())
                {
                    if (item.Socket != null)
                    {
                        item.Socket.Send(res);
                        LogHelper.InputLog("消息发送成功:" + res + "用户地址：" + item.Socket.ConnectionInfo.ClientIpAddress);
                    }
                    else
                    {
                        LogHelper.InputLog("步骤5");

                    }
                }
            }
            else
            {
                LogHelper.InputLog("无人连接，发送失败！groupname:" + groupName + ";groupValue:" + groupValue + ";参数：" + res);
            }
        }
        catch (Exception ex)
        {
            var ss = "无";
            if (ex.InnerException != null)
                ss = ex.InnerException.ToString();
            LogHelper.InputLog("websocket错误异常：" + ex.Message + "目前在线数量为：" + cc + ";详情错误信息：" + ss);
            throw;
        }
    }