在转到配置文件页面时，'profile_pic‘没有与之关联的文件，值错误显示

app.post('/upload', (req, res) => {
  if (!req.files || Object.keys(req.files).length === 0) {
    return res.status(400).send('No files were uploaded.');
  }

  let profile_pic = req.files.profile_pic;
  let uploadPath = __dirname + '/uploads/' + profile_pic.name;

  profile_pic.mv(uploadPath, function(err) {
    if (err) return res.status(500).send(err);
    // 更新数据库中的profile_pic字段为uploadPath
    db.updateUserProfilePic(userId, uploadPath, (err, result) => {
      if (err) return res.status(500).send(err);
      res.send('File uploaded!');
    });
  });
});

<img id="profilePic" src="{{profile_pic}}" alt="Profile Picture">
<script>
  document.addEventListener("DOMContentLoaded", function() {
    let profilePic = document.getElementById('profilePic');
    if (!profilePic.src || profilePic.src === "{{profile_pic}}") {
      profilePic.src = '/path/to/default/image.jpg'; // 设置默认头像
    }
  });
</script>