constructEvent is not working in the example

Problem

im using the provided example https://github.com/stripe/stripe-node/tree/master/examples/webhook-signing to check the sign (without changing any code, but just put the correct secret here is my test body that grep from the webhook request `{ "id": "evt_1HI8Y3G18iuNs10OgnHen3OH", "object": "event", "api_version": "2020-03-02", "created": 1597909859, "data": { "object": { "id": "pi_1HI8Y3G18iuNs10OOPlF55v4", "object": "payment_intent", "amount": 21000, "amount_capturable": 0, "amount_received": 0, "application": null, "application_fee_amount": null, "canceled_at": null, "cancellation_reason": null, "capture_method": "automatic", "charges": { "object": "list", "data": [], "has_more": false, "total_count": 0, "url": "/v1/charges?payment_intent=pi_1HI8Y3G18iuNs10OOPlF55v4" }, "client_secret": "pi_1HI8Y3G18iuNs10OOPlF55v4_secret_fBJ4VKg0NttX3X5wbN1BHmfoL", "confirmation_method": "automatic", "created": 1597909859, "currency": "hkd", "customer": null, "description": "Order #: SMY1597909859", "invoice": null, "last_payment_error": null, "livemode": false, "metadata": {}, "next_action": null, "o