#ReactServerErrorProvider

#Import

1import { ReactServerErrorProvider } from "alepha/react/router";

#Overview

Answers a browser navigation with an HTML error page instead of JSON.

ServerRouterProvider serializes every error as JSON, which is the right answer for an API and the wrong one for a hard navigation: the visitor gets {"status":503,…} painted as text on a white background, with no styles, no favicon and no way back.

The router already renders a real error page for anything a loader or a component throws — that path runs inside createLayers, which owns errorHandler. What never reached it is everything thrown around the render: use: middleware, and every server:onRequest hook. Those are not exotic. ServerNotReadyProvider throws 503 while the app is still booting, ServerRateLimitProvider throws 429, ServerAuthProvider throws 401 on a stale token. All three land on a first-time visitor, and all three used to answer with JSON.

This provider closes that gap from the react side, on the hook the server already offers for it: errorHandler emits server:onError first and stops as soon as a listener has set a status. So alepha/server needs no change, and an app that does not load the react router keeps the JSON behaviour exactly as it is.

Two conditions, both required:

• Accept: text/html. A browser navigation asks for HTML; fetch, $action sub-requests, curl and health checks send a wildcard or application/json and keep getting JSON. A bare wildcard never counts — that is what every programmatic client sends.
• React is loaded. Guaranteed by construction: this provider ships with alepha/react/router, so an API-only app has no such listener.