Array
(
    [error] => Array
        (
            [code] => 401
            [message] => Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.
            [status] => UNAUTHENTICATED
            [details] => Array
                (
                    [0] => Array
                        (
                            [@type] => type.googleapis.com/google.rpc.ErrorInfo
                            [reason] => CREDENTIALS_MISSING
                            [domain] => googleapis.com
                            [metadata] => Array
                                (
                                    [service] => fcm.googleapis.com
                                    [method] => google.firebase.fcm.v1.FcmService.SendMessage
                                )

                        )

                )

        )

)