code: function _wrap (handler, emitter) {
    return async (req, res) => {
      try {
        let response = await handler(req)
  
        await response.send(res)
      } catch (err) {
        // normalize
        if (! (err instanceof Error)) {
          err = new Error(`Non-error thrown: "${typeof err}"`)
        }
  
        // support ENOENT
        if (err.code === 'ENOENT') {
          err.expose = true
          err.status = 404
        }
  
        // send
        res.statusCode = err.status || err.statusCode || 500
        res.end()
  
        // delegate
        emitter.emit('error', err)
      }
    }
  }
docs: Wrap the request handler
  
  @param {Function} handler The request handler
  @param {EventEmitter} emitter
  @private