authentik/web/src/elements/messages/Middleware.ts

import { Middleware, ResponseContext } from "authentik-api";
import { gettext } from "django";
import { MessageLevel } from "./Message";
import { showMessage } from "./MessageContainer";

export class MessageMiddleware implements Middleware {

    post(context: ResponseContext): Promise<Response | void> {
        if (context.response.status >= 500) {
            showMessage({
                level: MessageLevel.error,
                message: gettext("API request failed"),
                description: `${context.init.method} ${context.url}: ${context.response.status}`
            });
        }
        return Promise.resolve(context.response);
    }
}