From 001be82c49bc0316c89c32f92110b546fac86c90 Mon Sep 17 00:00:00 2001
From: Kevin Thornton <krthornt@uci.edu>
Date: Mon, 4 May 2026 17:05:42 -0700
Subject: [PATCH] fix: correct bounds check on preorder root node

---
 src/sys/tree.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/sys/tree.rs b/src/sys/tree.rs
index 73583fa8..42c28bc9 100644
--- a/src/sys/tree.rs
+++ b/src/sys/tree.rs
@@ -378,7 +378,9 @@ impl<'a> PreorderNodeIterator<'a> {
     }
 
     fn new_from(tree: &'a LLTree, root: NodeId) -> Result<Self, TskitError> {
-        if root != NodeId::NULL && root != tree.virtual_root() && root < tree.treeseq.num_samples()
+        if root != NodeId::NULL
+            && root != tree.virtual_root()
+            && root.as_usize() < tree.treeseq.num_nodes_raw() as usize
         {
             Ok(PreorderNodeIterator {
                 current_root: NodeId::NULL,