From 7655b549b88d60276fd80459dea0b1865db05db4 Mon Sep 17 00:00:00 2001
From: Simon Fell <fellforce@gmail.com>
Date: Sun, 23 Feb 2025 15:22:23 -0800
Subject: [PATCH] fix for bounds panic in n16 delete

---
 art_test.go | 11 ++++++++++-
 node16.go   |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/art_test.go b/art_test.go
index 79ecfcf..fde7f1d 100644
--- a/art_test.go
+++ b/art_test.go
@@ -68,9 +68,18 @@ func Test_GrowNode(t *testing.T) {
 		// test that the node is grown to the relevant type
 		{1, &Stats{Keys: 1}},
 		{2, &Stats{Node4s: 1, Keys: 2}},
-		{12, &Stats{Node16s: 1, Keys: 12}},
+		{3, &Stats{Node4s: 1, Keys: 3}},
+		{4, &Stats{Node4s: 1, Keys: 4}},
+		{5, &Stats{Node16s: 1, Keys: 5}},
+		{14, &Stats{Node16s: 1, Keys: 14}},
+		{15, &Stats{Node16s: 1, Keys: 15}},
+		{16, &Stats{Node16s: 1, Keys: 16}},
+		{17, &Stats{Node48s: 1, Keys: 17}},
 		{40, &Stats{Node48s: 1, Keys: 40}},
+		{48, &Stats{Node48s: 1, Keys: 48}},
+		{49, &Stats{Node256s: 1, Keys: 49}},
 		{200, &Stats{Node256s: 1, Keys: 200}},
+		{256, &Stats{Node256s: 1, Keys: 256}},
 	}
 	for _, tc := range cases {
 		t.Run(fmt.Sprintf("children %d", tc.children), func(t *testing.T) {
diff --git a/node16.go b/node16.go
index afa8520..4f6aede 100644
--- a/node16.go
+++ b/node16.go
@@ -131,9 +131,9 @@ func (n *node16[V]) removeChild(k byte) {
 	}
 	copy(n.key[idx:], n.key[idx+1:int(n.childCount)])
 	copy(n.children[idx:], n.children[idx+1:int(n.childCount)])
+	n.childCount--
 	n.key[int(n.childCount)] = 0
 	n.children[int(n.childCount)] = nil
-	n.childCount--
 }
 
 func (n *node16[V]) shrink() node[V] {