async_handle_request.js

const Layer = require('express/lib/router/layer');
Layer.prototype.handle_request = async function handle(req, res, next) {
  var fn = this.handle;

  if (fn.length > 3) {
    // not a standard request handler
    return next();
  }

  try {
    await fn(req, res, next);
  } catch (err) {
    next(err);
  }
};

server.js

const http = require('http');
const morgan = require('morgan');
require('./async_handle_request');
const app = require('express')();

app.get('/', (req, res, next) => {
  res.json({ message: "ok" })
});
app.use(morgan('tiny'));
app.get('/ok', (req, res, next) => {
  res.json({ message: "ok really" });
  next();
});
app.get('/rejects', async (req, res, next) => {
  throw new Error('I stink');
});
// Fallback handler
app.use((req, res) => {
  if (!res.headersSent) {
    res.status(404);
    res.json({ error: 'Not Found' });
  }
});

app.use(errorHandler);

/* istanbul ignore next */
// eslint-disable-next-line no-unused-vars
function errorHandler(err, req, res, next) {
  // We must delegate to the Express error handler if the response has started
  if (res.headersSent) {
    return next(err);
  }

  // Try to detect common http codes that modules attach to errors
  let code = parseInt(err.statusCode || err.code || err.status);
  if (!(code >= 400 && code < 600)) {
    code = 500;
  }
  res.status(code);

  const message = err.message || http.STATUS_CODES[res.statusCode] || 'Internal Server Error';

  res.json({ error: message });
}

module.exports = app;
if (require.main === module) {
  const server = http.Server(app);
  server.listen(process.env.PORT || 1337, function () {
    const addr = this.address();
    console.log(`Express server listening on port ${addr.port}`);
  });
}