新手想用trading view信号自动交易币安btc永续合约，部署机器人后出现 ，错误 Ct 合约设置为空。求大神帮看一下怎么做。。
代码是复制的TradingViewWebHook信号执行策略（教学）
/*

• 交互命令字符串格式
  action:amount
  action: buy , sell , long , short , cover_long , cover_short, spk , bpk

• 交易所类型
  eType变量取值: 0 spot , 1 futures

• TV文档链接
  https://www.tradingview.com/pine-script-docs/en/v4/Quickstart_guide.html
  https://cn.tradingview.com/chart/8xfTuX7F/

• TV webhook 发送请求
  https://www.fmz.cn/api/v1?access_key=xxx&secret_key=yyyy&method=CommandRobot&args=[186515,"action:amount"]

• 引用类库
  引用数字货币交易类库
  */

// 参数
// var IsMarketOrder = false
// var QuotePrecision = 2
// var BasePrecision = 2

// 期货参数
// var Ct = ""

// 全局变量
var BUY = "buy"
var SELL = "sell"
var LONG = "long"
var SHORT = "short"
var COVER_LONG = "cover_long"
var COVER_SHORT = "cover_short"
var SPK = "spk"
var BPK = "bpk"

function main() {
// 清空日志，如不需要，可以删除
LogReset(1)

// 设置精度
exchange.SetPrecision(QuotePrecision, BasePrecision)

// 识别期货还是现货
var eType = 0
var eName = exchange.GetName()
var patt = /Futures_/
if (patt.test(eName)) {
Log("添加的交易所为期货交易所：", eName, "#FF0000")
eType = 1
if (Ct == "") {
throw "Ct 合约设置为空"
} else {
Log(exchange.SetContractType(Ct), "设置合约：", Ct, "#FF0000")
}
} else {
Log("添加的交易所为现货交易所：", eName, "#32CD32")
}

var lastMsg = ""
var acc = _C(exchange.GetAccount)
while(true) {
var cmd = GetCommand()
if (cmd) {
// 检测交互命令
lastMsg = "命令:" + cmd + "时间:" + _D()
var arr = cmd.split(":")
if (arr.length != 2) {
Log("cmd信息有误：", cmd, "#FF0000")
continue
}

var action = arr[0]
var amount = parseFloat(arr[1])

if (eType == 0) {
if (action == BUY) {
var buyInfo = IsMarketOrder ? exchange.Buy(-1, amount) : $.Buy(amount)
Log("buyInfo:", buyInfo)
} else if (action == SELL) {
var sellInfo = IsMarketOrder ? exchange.Sell(-1, amount) : $.Sell(amount)
Log("sellInfo:", sellInfo)
} else {
Log("现货交易所不支持！", "#FF0000")
}
} else if (eType == 1) {
var tradeInfo = null
var ticker = _C(exchange.GetTicker)
if (action == LONG) {
exchange.SetDirection("buy")
tradeInfo = IsMarketOrder ? exchange.Buy(-1, amount) : exchange.Buy(ticker.Sell, amount)
} else if (action == SHORT) {
exchange.SetDirection("sell")
tradeInfo = IsMarketOrder ? exchange.Sell(-1, amount) : exchange.Sell(ticker.Buy, amount)
} else if (action == COVER_LONG) {
exchange.SetDirection("closebuy")
tradeInfo = IsMarketOrder ? exchange.Sell(-1, amount) : exchange.Sell(ticker.Buy, amount)
} else if (action == COVER_SHORT) {
exchange.SetDirection("closesell")
tradeInfo = IsMarketOrder ? exchange.Buy(-1, amount) : exchange.Buy(ticker.Sell, amount)
} else if (action == SPK) { // 卖出平多仓，卖出开空仓
exchange.SetDirection("closebuy")
var tradeInfo1 = IsMarketOrder ? exchange.Sell(-1, amount) : exchange.Sell(ticker.Buy, amount)
exchange.SetDirection("sell")
var tradeInfo2 = IsMarketOrder ? exchange.Sell(-1, amount) : exchange.Sell(ticker.Buy, amount)
tradeInfo = [tradeInfo1, tradeInfo2]
} else if (action == BPK) { // 买入平空仓，买入开多仓
exchange.SetDirection("closesell")
var tradeInfo1 = IsMarketOrder ? exchange.Buy(-1, amount) : exchange.Buy(ticker.Sell, amount)
exchange.SetDirection("buy")
var tradeInfo2 = IsMarketOrder ? exchange.Buy(-1, amount) : exchange.Buy(ticker.Sell, amount)
tradeInfo = [tradeInfo1, tradeInfo2]
} else {
Log("期货交易所不支持！", "#FF0000")
}
if (tradeInfo) {
Log("tradeInfo:", tradeInfo)
}
} else {
throw "eType error, eType:" + eType
}
acc = _C(exchange.GetAccount)
}
var tbl = {
type : "table",
title : "状态信息",
cols : ["数据"],
rows : []
}
tbl.rows.push([JSON.stringify(acc)])
LogStatus(_D(), eName, "上次接收到的命令：", lastMsg, "\n", "" + JSON.stringify(tbl) + "")
Sleep(1000)
}
}