使用nodejs上传图片到七牛报错

Question

在本地开发是ok的，部署到服务器之后在生成token的时候报错

TypeError: Key must be a buffer

上传代码如下：

const qiniu = require('qiniu');
const bucket = 'my-bucket-name';
const qiniuCallbackUrl = 'http://api.mysite.com/qiniu';
const qiniuCallbackBody = {
    name: '$(fname)',
    hash: '$(etag)',
    imageInfo: '$(imageInfo)',
    key: '$(key)',
    imgUrl: `${qiniuHost}/$(key)`
}

qiniu.conf.ACCESS_KEY = process.env.QINIU_AK;
qiniu.conf.SECRET_KEY = process.env.QINIU_SK;

Img.newImg = function * () {
    let body = this.request.body;
    let parts = parse(this);
    let part;
    let localPath = path.join(os.tmpdir(), Math.random().toString());
    let stream = fs.createWriteStream(localPath);
    let key, token;
    
    while ((part = yield parse(this))) {
        // let stream = fs.createWriteStream(path.join(os.tmpdir(), Math.random().toString()));
        part.pipe(stream);
        key = part.filename;
        token = uptoken(bucket, key);
        let res = yield uploadFile(token, key, localPath);
        this.body = res;
    }
}

function uptoken(bucket, key) {
    let scope = bucket + ":" + key;
    let putPolicy = new qiniu.rs.PutPolicy(scope);
    putPolicy.callbackUrl = qiniuCallbackUrl;
    putPolicy.callbackBody = qs.stringify(qiniuCallbackBody).replace(/\%24/g, '$');
    return putPolicy.token(); // 这行报错 TypeError: Key must be a buffer
}

function uploadFile(uptoken, key, localFile) {
    return new Promise((resolve, reject) => {
        let extra = new qiniu.io.PutExtra();
        qiniu.io.putFile(uptoken, key, localFile, extra, function(err, ret) {
            if(!err) {
                // 上传成功， 处理返回值
                resolve(ret);  
            } else {
                // 上传失败， 处理返回代码
                reject(err);
            }
        });
    })
    
}

上传图片的代码是参照koa example里面写的，感觉上传到七牛云的逻辑不能写在while里面，但是在外面又访问不到文件名，我想把文件名当做key 传到七牛。
请各路大神帮我看看哪里写错了