将数据导出到csv时，获取到`发送到客户端后无法设置头部`

const express = require('express');
const fs = require('fs');
const csv = require('csv-parser');

const app = express();

app.get('/export', (req, res) => {
  const data = [
    { name: 'John', age: 30 },
    { name: 'Jane', age: 25 },
    { name: 'Bob', age: 35 }
  ];

  const filename = 'data.csv';

  res.setHeader('Content-Type', 'text/csv');
  res.setHeader('Content-Disposition', `attachment; filename=${filename}`);

  const stream = fs.createWriteStream(filename);

  stream.write('Name,Age\n');

  data.forEach((item) => {
    stream.write(`${item.name},${item.age}\n`);
  });

  stream.end();

  stream.on('finish', () => {
    res.sendFile(filename, { root: __dirname });
  });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});