Error Handler

Any error occurring during a request lifecycle is intercepted by the error handler.

You can customize the default error-handling behavior by defining a custom error handler using the onError method of the Galbe instance.

const galbe = new Galbe()
galbe.onError(customErrorHandler)

Note

onError can be called more than once. Each registered handler is invoked, in registration order, for every error. The last truthy return value is used as the response.

Definition

The error handler should be a function that takes two arguments: an Error and a Context. This function may return a Response type.

galbe.onError((error, ctx) => {
  if (error.status === 500) {
    return new Response(`Server error ❌`, { status: 500 })
  }
  if (error.status === 404) {
    return new Response(`Not found 🔎`, { status: 404 })
  }
})

The error argument can be any type of error thrown by your application. If the error originates from the Galbe framework, it will be an instance of RequestError.

For example, the Router throws a RequestError with a 404 status if no route matches the incoming request path, or 405 if the path matches but the method is not allowed. Similarly, the parser and validator throw a RequestError with a 400 status in case of invalid input.

Request Error

The RequestError class represents a runtime request error in Galbe. It accepts three optional fields: status (defaults to 400), payload, and headers.

If your application throws a RequestError instance, Galbe will, by default, construct a Response from your RequestError and send it back to the client.

import { RequestError } from 'galbe'

galbe.get('/coffee', () => {
  throw new RequestError({ status: 418, payload: '🫖' })
})

When called, the above endpoint responds:

$ curl -i http://localhost:3000/coffee

HTTP/1.1 418 I'm a teapot

Content-Type: text/plain

Content-Length: 4

🫖

Note

When the payload is a string, the response is sent with Content-Type: text/plain. Any other payload is JSON-stringified and sent with Content-Type: application/json. You can override this by passing headers to the RequestError.