问cos-nodejs-sdk-v5分片上传报错怎么回事？

ENOENT: ENOENT: no such file or directory, stat 'files'
message: "ENOENT: no such file or directory, stat 'files'"
errno: -2
code: "ENOENT"
syscall: "stat"
path: "files"
error: {"message":"ENOENT: no such file or directory, stat 'files'","errno":-2,"code":"ENOENT","syscall":"stat","path":"files"}
headers: {"Access-Control-Allow-Origin":"*","vary":"Origin"}
pid: 61504

// 分片上传
 cos.sliceUploadFile({
        Bucket: config.Bucket,
        Region: config.Region,
        Key: `${config.path}/${appId}/${stream.filename}`,
        FilePath: 'files',
        // Body: fs.createReadStream(stream.filepath),
 }, function(err, data) {
        if (err) {
               reject(err);
        } else {
               formData.code = 0;
               formData.fileInfo.fileUrl = `https://${data.Location}`;
               formData.msg = 'success';
               resolve(formData);
        }
 });