Warning: Undefined property: stdClass::$access_token in /home/amzgreatvaluesto/public_html/amz_sp_sds/listCatalogItems.php on line 39

{
  "errors": [
    {
      "code": "Unauthorized",
      "message": "Access to requested resource is denied.",
      "details": "Access token is missing in the request header."
    }
  ]
}