Change not found callback.

src/Libs/Router.php

@@ -19,10 +19,12 @@ class Router {
     private static $put = [];
     private static $delete = [];
     private static $last;
-    public static $notFoundCallBack = function () {
+    public static $notFoundCallBack = 'Libs\Router::defaultNotFound';
+
+    private static function defaultNotFound () {
         header("HTTP/1.0 404 Not Found");
         echo '<h2 style="text-align: center;margin: 25px 0px;">Error 404 - Página no encontrada</h2>';
-    };
+    }
 
     private function __construct() {}