Global Error Handling

A safe error response is useless if one forgotten handler lets a panic escape. In Go, recovery middleware gives you one final boundary between unexpected failures and public responses.

Install a deferred function before calling the next handler. If downstream code panics, recover can capture the value so the middleware can log it and return a generic response:

func recoverPanics(next http.Handler) http.Handler {
    return http.HandlerFunc(func(responseWriter http.ResponseWriter, request *http.Request) {
        defer func() {
            if recovered := recover(); recovered != nil {
                slog.Error("unhandled panic", "value", recovered)
                http.Error(responseWriter, "Something went wrong", http.StatusInternalServerError)
            }
        }()

        next.ServeHTTP(responseWriter, request)
    })
}

Some failures are expected or handler-specific and should be handled where they occur. A missing concert ticket should get a deliberate 404, and invalid checkout input should get a client-safe 400. Recovery middleware is a last resort for unexpected panics, not a replacement for ordinary error handling.