Report errors to Sentry

Use this when you want unexpected failures in your error tracker without a report at every call site. The client’s onError runs once for each call that fails, so one function covers every endpoint.

Sentry stands for your error tracker; getUser is the Quick start endpoint.

import { createApi } from 'liaise'

const api = createApi({
  baseUrl: '/api',
  requests: { getUser },
  // Called once per failed call, after retries. Never for 'abort': you cancelled it.
  onError: error => {
    if (error.kind === 'http' && error.status < 500) return // expected 4xx, not a bug
    Sentry.captureException(error, {
      extra: { kind: error.kind, url: error.request.url, status: error.status },
    })
  },
})

A 500 reaches Sentry with its kind, URL and status. A 404, or a call you cancelled, doesn’t.

What reaches Sentry

onError runs once per failed call, after all your middleware. A call that retryMiddleware rescues is never reported, and calls that share one failed request are reported once.
It is never called for 'abort', because you cancelled that call. A missed timeout is reported.
The first line of onError skips 4xx responses. A 404 or a 422 is an answer your code handles, not a bug. Everything else reaches Sentry: a 5xx, a network failure, a missed deadline, a body that didn’t parse and a middleware that threw (The six kinds).
It only watches. The caller gets the same Result either way.

What to send

ApiError isn’t an Error, so it carries no stack trace or message of its own. Pass the fields you want to see in extra, as above. Every field is listed under ApiError.

When to use a middleware instead

Use a middleware when you need timing, or the request before it’s sent, or want to report for some endpoints only. Example: report server errors has the middleware version.

Next: Upload and download files sends a file as FormData and reads one back as a Blob.