Further optimization

Author: greymistcube

src/Libplanet.RocksDBStore/RocksDBStore.cs

@@ -1836,9 +1836,13 @@ private IEnumerable<BlockHash> IterateIndexesPruned(
             }
 
             long count = 0;
+            long limitUpperBound = CountIndex(chainId) - offset;
+            long actualLimit = limit is { } l
+                ? Math.Min(l, limitUpperBound)
+                : limitUpperBound;
             foreach (BlockHash hash in IterateIndexesInnerPruned(chainId, offset))
             {
-                if (count >= limit)
+                if (count >= actualLimit)
                 {
                     yield break;
                 }