Javascript 尝试加载根路径时，应用程序返回错误

我编写了一个简单的javascript文件，允许我通过web浏览器查看数据库中的值。它以前工作过，但现在返回以下错误：

_http_outgoing.js:494
    throw new Error('Can\'t set headers after they are sent.');
    ^

Error: Can't set headers after they are sent.
    at validateHeader (_http_outgoing.js:494:11)
    at ServerResponse.setHeader (_http_outgoing.js:501:3)
    at ServerResponse.header (issuesDB/node_modules/express/lib/response.js:767:10)
    at ServerResponse.send (issuesDB/node_modules/express/lib/response.js:170:12)
    at ServerResponse.json (issuesDB/node_modules/express/lib/response.js:267:15)
    at ServerResponse.send (issuesDB/node_modules/express/lib/response.js:158:21)
    at db.all (issuesDB/app.js:23:21)
    at Statement.errBack (issuesDB/node_modules/sqlite3/lib/sqlite3.js:16:21)

我非常确定我没有改变代码或数据库中的任何内容，所以不确定为什么它现在失败了，任何帮助都将不胜感激

代码如下：

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const morgan = require('morgan');
const sqlite = require('sqlite3');
const db = new sqlite.Database('./issues.sqlite');
const dbname = 'issueInventory';
const PORT = process.env.PORT || 4001

app.use(bodyParser.json());
app.use(morgan('dev'));


app.get('/', (req,res,next) => {
  db.all(`select * from $dbname;`,
    {
      $dbname: dbname
  },
  (err,rows) =>{
    if (err) {
      res.status(500).send(`Something went wrong, we are working on it`)
    }
    res.status(200).send({issues: rows})
  });
});


app.listen(PORT, () => {
  console.log(`Application Server listening on ${PORT}`)
});

module.exports = app;

---

这就像你返回了两个响应。您错过了

return

语句

if (err) return res.status(500).send('Something went wrong, we are working on it');
res.status(200).send({issues: rows});

---

这就像你返回了两个响应。您错过了

return

语句

if (err) return res.status(500).send('Something went wrong, we are working on it');
res.status(200).send({issues: rows});

---

事实上，现在它已恢复运行！我还删除了表名的占位符，猜测它也不喜欢那个部分。非常感谢您的帮助：）的确-现在它已经恢复运行了！我还删除了表名的占位符，猜测它也不喜欢那个部分。非常感谢您的帮助：）