问从GCP bucket下载文件会返回一个带有nodeJS的空文件

EN

const gc = require('./config')
const bucket = gc.bucket('my_bucket') // nombre del bucket en GCS
// The ID of your GCS bucket
const downloadJsonFile = async (req, res) => {
  fileName=req.body.fileName
  const bucketName = "my_bucket";

  // The path to which the file should be downloaded  
  console.log("dirname de download",__dirname)
  const destFileName = "./public/result.json"
  
  // Creates a client  

  async function downloadFile() {
    const options = {
      destination: destFileName,
    };

    // Downloads the file
    await bucket.file(fileName).download(options);

    console.log(
      `gs://${bucketName}/${fileName} downloaded to ${destFileName}.`
    );
  }

  downloadFile().catch(console.error);  
};

module.exports={
    downloadJsonFile
}