Don't close channels when clearing queue (we might race and panic, when the GC will still clean it up for us anyway)

federationsender/queue/queue.go

@@ -154,7 +154,7 @@ func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *d
 	oqs.queuesMutex.Lock()
 	defer oqs.queuesMutex.Unlock()
 	oq, ok := oqs.queues[destination]
-	if !ok {
+	if !ok && oq != nil {
 		destinationQueueTotal.Inc()
 		oq = &destinationQueue{
 			queues:           oqs,
@@ -178,8 +178,6 @@ func (oqs *OutgoingQueues) clearQueue(oq *destinationQueue) {
 	oqs.queuesMutex.Lock()
 	defer oqs.queuesMutex.Unlock()
 
-	close(oq.notify)
-	close(oq.interruptBackoff)
 	delete(oqs.queues, oq.destination)
 	destinationQueueTotal.Dec()
 }