A simple middleware for Slim4 framework that print JSON message for 404 Not Found. Usage is very simple, just enable this Middleware (in the Middleware part of your Slim4 Project) with:

<?php

use PerSeo\Middleware\HttpException\Json\HttpExceptionMiddleware;

$app->add(HttpExceptionMiddleware::class);

After this, your Slim 4 project returns a JSON message for 404 Not Found.