Reg onPostStop is not executing statements inside method

#### Support plan

* *is this issue currently blocking your project?* (yes/no):no
* *is this issue affecting a production system?* (yes/no):no

#### Context

* *node 17.9.1*:
* *@hapi/hapi 20.2.1*:
* *node* (e.g. node, browser, native):
* *hapi* (e.g. hapi application, another framework, standalone, ...):
* *any other relevant information*:

#### How can we help?

```js
server.ext({
type: 'onPostStop',
method (request, reply) {
console.log('Application stopped');
},
});
```