On Chrome, transferring the port more than once causes an error:

```
const {port1, port2} = new MessageChannel();
window.postMessage('hello', '*', [port1])
window.postMessage('hello', '*', [port1])
> Uncaught DOMException: Failed to execute 'postMessage' on 'Window': Port at index 0 is already neutered.
    at <anonymous>:1:8
```

As a result of `PortFinder` polling the host, `PortProvider` could
respond multiple times, specially when the polling frequency is high.