Don't close the dying channel right away

Now that we have internal goroutines writing to it, we can't close it
arbitrarily or we risk a panic writing to a closed channel. Instead just write
nil, and have the receiver close it (since it knows nobody else is writing at
the moment).

consumer.go

@@ -364,11 +364,11 @@ func (child *partitionConsumer) Errors() <-chan *ConsumerError {
 }
 
 func (child *partitionConsumer) AsyncClose() {
-	// this triggers whatever worker owns this child to abandon it and close its trigger channel, which causes
+	// this triggers whatever broker owns this child to abandon it and close its trigger channel, which causes
 	// the dispatcher to exit its loop, which removes it from the consumer then closes its 'messages' and
 	// 'errors' channel (alternatively, if the child is already at the dispatcher for some reason, that will
 	// also just close itself)
-	close(child.dying)
+	child.dying <- nil
 }
 
 func (child *partitionConsumer) Close() error {
@@ -403,9 +403,9 @@ func (child *partitionConsumer) responseFeeder() {
 		case ErrOffsetOutOfRange:
 			// there's no point in retrying this it will just fail the same way again
 			// so shut it down and force the user to choose what to do
-			child.AsyncClose()
-			child.sendError(err)
 			Logger.Printf("consumer/%s/%d shutting down because %s\n", child.topic, child.partition, child.broker.broker.ID(), err)
+			child.sendError(err)
+			child.AsyncClose()
 		case ErrUnknownTopicOrPartition, ErrNotLeaderForPartition, ErrLeaderNotAvailable:
 			// these three are not fatal errors, but do require redispatching
 			child.dying <- err
@@ -601,6 +601,7 @@ func (bc *brokerConsumer) updateSubscriptionCache(newSubscriptions []*partitionC
 		case err := <-child.dying:
 			if err == nil {
 				Logger.Printf("consumer/broker/%d closed dead subscription to %s/%d\n", bc.broker.ID(), child.topic, child.partition)
+				close(child.dying)
 				close(child.trigger)
 			} else {
 				Logger.Printf("consumer/broker/%d abandoned subscription to %s/%d because %s\n", bc.broker.ID(), child.topic, child.partition, err)