Facing error in code - App life cycle events (webhook events)

Hi,

We submitted the App in the marketplace .

To know about the details of App installation and uninstallation, we are utilizing webhook events, and we have written the following code according to the documentation. However, we are encountering errors in the code such as

JsonWebTokenError: invalid signature
at C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\jsonwebtoken\\verify.js:171:19
at getSecret (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\jsonwebtoken\\verify.js:97:14)
at module.exports [as verify] (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\jsonwebtoken\\verify.js:101:10)
at C:\\Users\\priya\\Downloads\\monday.com webhook\\server.js:11:26
at Layer.handle [as handle_request] (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\layer.js:95:5)
at next (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\route.js:144:13)
at Route.dispatch (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\route.js:114:3)
at Layer.handle [as handle_request] (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\layer.js:95:5)
at C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\index.js:284:15
at Function.process_params (C:\\Users\\priya\\Downloads\\monday.com webhook\\node_modules\\express\\lib\\router\\index.js:346:12)

Sample Code for your reference:

app.post("/action", function(req, res) {
    res.status(200).send({})
    const token = req.headers.authorization;
    const decoded = jwt.verify(token, “MY_SIGNING_SECRET”);
    const subscription = decoded.subscription;
})