nuxt中如何设置追踪推荐人代码?写在前端middleware或者nuxtServerInit都报错

Question

有个需求是创建一个邀请链接,
然后需要被邀请的时候即使没登录也要记录这个邀请人,
然后注册的时候也记录邀请人,

我的思路是保存在session,虽然能保存成功,但是有个cookie的报错,代码和错误信息如下,
好像是nuxt已经render了,render后修改cookie就会有错误,
额,然后请问大神们应该怎么写类似nuxt渲染,但是需要服务器配合的逻辑?

nuxtServerInit ({ commit }, { req , query }) {
if(query.inviter){
if (!trance) {
trance={}
console.log('req.session.trance.inviter',req.session.trance)
}
if(trance.inviter!=query.inviter){
trance.inviter=query.inviter
}
console.log('req.session.trance.inviter',req.session.trance)
}
}

错误信息

Error: Can't set headers after they are sent.
at validateHeader (_http_outgoing.js:504:11)
at ServerResponse.setHeader (_http_outgoing.js:511:3)
at Cookies.set (/www/wwwroot/miaodetao/source/node_modules/cookies/index.js:115:13)
at /www/wwwroot/miaodetao/source/node_modules/koa-session2/index.js:39:21
at 
at process._tickCallback (internal/process/next_tick.js:169:7)