Fix SocketIpcHub::accept if already cancelled

Relates to #199.

src/Ipc/SocketIpcHub.php

@@ -165,9 +165,10 @@ public function accept(string $key, ?Cancellation $cancellation = null): Resourc
  $this->queued = true;
  }
 
- $this->waitingByKey[$key] = $suspension = EventLoop::getSuspension();
-
  $cancellation = $cancellation ?? new NullCancellation();
+ $cancellation->throwIfRequested();
+
+ $this->waitingByKey[$key] = $suspension = EventLoop::getSuspension();
  $cancellationId = $cancellation->subscribe(function (CancelledException $exception) use ($suspension) {
  $suspension->throw($exception);
  });