Update readFiles method in SapFileController to improve user identification in error responses

app/Http/Controllers/SapFileController.php

@@ -43,7 +43,7 @@ class SapFileController extends Controller
                     'path_checked' => $path,
                     'is_dir' => $isDir,
                     'is_readable' => $isReadable,
-                    'php_user' => get_current_user(),
+                    'php_user' => exec('whoami'),
                 ]
             ], 500);
         }