Calling HttpServer's stop method in binding-http returns nothing

The following problem occurred. I apologize for the inconvenience and would appreciate your confirmation.
I would appreciate it if you could tell me if I am calling it the wrong way, etc.

# Problem

Nothing is returned when I call the stop method of HttpServer of Binding-http.
This problem may occur if the property is being observed from the client.

# environment

* Mac(Apple siicon)
* OS: Sonoma 14.1
* nodejs: v18 or v20
* node-wot: 0.8.12

# Steps to reproduce

get the following code

https://github.com/hidetak/test-node-wot/tree/main/no-stop-httpserver

1. $ npm install
1. $ npm run start:server
1. open new terminal
1. $ npm run start:client
1. After 10 seconds have elapsed since the server was started, the termination process begins (The following text will appear in the terminal where the server is run)
```
[debug] endServient called.
[debug] server destroyed.
```
If 3 and 4 are not performed, the following is displayed and appears to be correctly terminated.
```
[debug] endServient called.
[debug] server destroyed.
[debug] server stopped.
[debug] servient shutdown.
```