cleanup & comment

controllers/SiteController.php

@@ -253,7 +253,7 @@ class SiteController {
 
         if (!file_exists($availableConfig)) {
             http_response_code(404);
-            echo json_encode(['error' => 'Configuration file not found']);
+            echo json_encode(['error' => $availableConfig . ' file not found']);
             return;
         }