// async-route.js
module.exports = handler => async (req, res, next) => {
  try {
    await handler(req, res, next)
  } catch (err) {
    next(err)
  }
}

// your-route.js
exports.sign_in = asyncRoute(async (req, res) => {
  const { body } = req;
  const { email, password } = body;

  const agent = await Agent.findOne({ email: email })
  if (!agent) return res.status(403).send('Not authenticated')

  const isPasswordCorrect = await bcrypt.compare(password, agent.password)
  if (!isPassWordCorrect) return res.status(403).send('Not authenticated')

  ...
})

// error-handler.js
exports.errorHandler = (err, req, res) => {
  // Often you won't send the error message/stack back to the client as it could expose something unwanted
  // Instead you would log it to your own error logging
  const statusCode = err.status || 500
  res.status(statusCode)
}