I am trying to make a rust app that can create, start & stop multiple simple REST servers.
For this, I use rouille.

I store the serverInstances using a hashMap behind a lazyLock:

struct ServerInstance {
    ...
    stop: (JoinHandle<()>, Sender<()>),
}

static SERVER_INSTANCES: LazyLock<Mutex<HashMap<usize, ServerInstance>>> =
    LazyLock::new(|| Mutex::new(HashMap::new()));

async fn start_server(id: usize, port: i16) {
    let server = Server::new(format!("0.0.0.0:{}", port), |request| {
        Response::text("hello world")
    })
    .unwrap();
    SERVER_INSTANCES.lock().unwrap().insert(
        id,
        ServerInstance { ..., stop: server.stoppable() },
    );
}

However, when I try to stop the server using this function:

fn stop_server_command(id: usize) {
    if let Some(instance) = SERVER_INSTANCES.lock().unwrap().get(&id) {
        let (handler, signal) = &instance.stop;
        signal.send(()).unwrap();
        handler.join().unwrap();
//      ^^^^^^^ ------ `*handler` moved due to this method call
    }
}

I get this error on handler.join():

error[E0507]: cannot move out of `*handler` which is behind a shared reference
    --> srclib.rs:47:9
     |
47   |         handler.join().unwrap();
     |         ^^^^^^^ ------ `*handler` moved due to this method call
     |         |
     |         move occurs because `*handler` has type `std::thread::JoinHandle<()>`, which does not implement the `Copy` trait
     |
note: `std::thread::JoinHandle::<T>::join` takes ownership of the receiver `self`, which moves `*handler`

Any ideas on how I should handle this?