slim 3 gist 7

index.php

<?php
$app->add(function ($req, $res, $next) {
    //DO SOMETHING BEFORE THE REQUEST IS PROCESSED

    $res = $next($req, $res); //PROCESS THE REQUEST

    //DO SOMETHING AFTER THE REQUEST HAS BEEN PROCESSED
    if ($res->getStatusCode() > 500) {
        //Do something with a server error, maybe email someone or submit a bug report
    }

    //Continue rendering
    return $res;
});