upd

src/VkUser.php

@@ -35,7 +35,7 @@ class VkUser implements ResourceOwnerInterface
     /**
      * Helper for getting user data
      */
-    protected function getField(string $key): mixed|null
+    protected function getField(string $key): mixed
     {
         return !empty($this->response[$key]) ? $this->response[$key] : null;
     }