modify default controller if needed

mvc/app/libs/Core.php

@@ -21,12 +21,12 @@
             
             // print_r($this->getURL());
             $url = $this->getURL();
-
-            if (file_exists('../app/controllers/' . ucwords($url[0]) . '.php')) {
-                $this->defaultController = ucwords($url[0]);
-                unset($url[0]);
+            if(isset($url[0])){
+                if (file_exists('../app/controllers/' . ucwords($url[0]) . '.php')) {
+                    $this->defaultController = ucwords($url[0]);
+                    unset($url[0]);
+                }
             }
-            
             require_once('../app/controllers/' . $this->defaultController . '.php');
             $this->defaultController = new $this->defaultController;
         }