Never wait NextMsg's bound for a dead letter held already overcounts (issue 728)

internal/link/deadletters.go

@@ -607,7 +607,16 @@ func AgingDeadLetters(js nats.JetStreamContext, held map[string]int) (map[string
 		if err != nil {
 			return nil, fmt.Errorf("the dead letters of %s cannot be read: %w", key, err)
 		}
-		for i := 0; i < n; i++ {
+		// held can count more than DEAD_LETTERS still holds for this consumer — one aged out,
+		// delivered again or dropped since it was counted (novox/hq issue 728 review round 1): read
+		// the ordered consumer's pending count once, from right when it was subscribed, and look for
+		// at most that many messages, so a look never waits out NextMsg's bound for one that is not
+		// there. That bound stays only as a guard against a pending count that is itself stale.
+		limit := n
+		if pending, err := sub.InitialConsumerPending(); err == nil && int(pending) < limit {
+			limit = int(pending)
+		}
+		for i := 0; i < limit; i++ {
 			m, err := sub.NextMsg(2 * time.Second)
 			if errors.Is(err, nats.ErrTimeout) {
 				break // delivered again, dropped or aged out since they were counted