How to revoke access token in Action on Google SDK

Hi, I want to revoke a token in a specific action returning a 401 error to the request (https://developers.google.com/actions/identity/oauth2-implicit-flow#revoke_tokens). I have not found how to do it with the “action-on-google” SDK and I have tried to do it by adding a middleware in my app, checking if the action of the request is the expected action and finally sending a response with status 401 and the payload JSON. My code:

const app = express();
const assistant = dialogflow();     // Integration with dialogflow
...
app.use((req, res, next) => {
	console.log('Middleware!');
	if(req.body.queryResult.action === EXPECTED_ACTION) {
		const response = {
			"payload": {
				"google": {
					"expectUserResponse": false,
					"richResponse": {
						"items": [
							{
								"simpleResponse": {
									"textToSpeech": "Good bye and have a nice day!"
								}
							}
						]
					},
					"userStorage": "{\"data\":{}}"
				}
			}
		};
		res.status(401).send(response);
		return;
	}
	next();
});

app.use(bodyParser.json(), assistant);

Doing the res.status(401).send(response); the Google Assistant revokes the token but the app crashes and it does not show the SimpleResponse. If I change the status to 200 (success) the Google Assistant shows the SimpleResponse but it does not revokes the token.

Is there any method in “actions-on-google-nodejs” SDK to revoke the token or send a 401 error with a message?

Thanks

[florent33700]

The UnauthorizedError exception does not seem to clear the access token anymore. However, It worked before.

[florent33700]

I have the same problem, the application crashes when I return code 401. Would anyone have a solution to post a message before leaving?