small bug fix where ptero id validation stopped working

app/Http/Controllers/Admin/UserController.php

@@ -83,7 +83,7 @@ class UserController extends Controller
             "role" => Rule::in(['admin', 'mod', 'client', 'member']),
         ]);
 
-        if (is_null($this->pterodactyl->getUser($request->input('pterodactyl_id')))) {
+        if (empty($this->pterodactyl->getUser($request->input('pterodactyl_id')))) {
             throw ValidationException::withMessages([
                 'pterodactyl_id' => ["User does not exists on pterodactyl's panel"]
             ]);