Server Start-Stop "restart" exception

[Alex Toth]

Scenario:

1. Start server
2. Stop server
3. Start server
4. Stop server <- at this point a TimerAwaitable is already disposed in the server component
   If we remove readonly keyword from _timerAwaitable and move its initialization from ctor to StartAsync() we could start-stop the server as many times as we want without throwing any exception.

Shall I PR it or it is intentionally done?

[David Fowler]

Yes please, send the fix.