Firebase FCM (Javascript): Error when request permission (Error status = 500)

I'm new to Firebase Cloud Messaging and I need to implement notifications in my webapp. If the browser requests notification for the first time there is no error occurred and the token fetched successfuly. But if I delete the notification from the browser parametre (I use Chrome) and ask for permission again, it shows me an error in the console.

DELETE https://fcmregistrations.googleapis.com/v1/projects/teak-perigee-*****/registrations/dcVW8MdcapIy5CrSqGutkj:APA91bFoslZEsjgIk16CUfol*****************

FirebaseError: Messaging: A problem occured while unsubscribing the user from FCM: FirebaseError: Messaging: A problem occured while unsubscribing the user from FCM: Internal error encountered. (messaging/token-unsubscribe-failed). (messaging/token-unsubscribe-failed).

Actually the token is fetched even this error occurs. but in this situation I handle the new token in the catch block of the promise. This is my code when permission is fired:

askForPermissioToReceiveNotifications = () => {

    const messaging = firebase.messaging();

   Notification.requestPermission().then(async (permission) => {

    if(permission == 'granted') {

        try {

            const token = await messaging.getToken();

            if(token) {

                console.log(token);
                return token;
            }

            else {
                console.log('No Instance ID token available. Request permission to generate one.');
            }
        }

        catch(error) {

            console.log('An error occurred while retrieving token. ', error);


            //BUT THE NEW TOKEN SUCCESSFULY FETCHED
            const token = await messaging.getToken();

            if(token) {

                console.log(token);
                return token;
            }

            else {
                console.log('No Instance ID token available. Request permission to generate one.');
            }
        }
    }

})
.catch(error => console.log(error));

}

I don't know if I miss something and I hope I can find a solution.