From ef2fca30067eb695b714bc0b4e051768a7dc7311 Mon Sep 17 00:00:00 2001
From: Logan <logan@lightscale.io>
Date: Fri, 25 Oct 2024 11:54:24 +0900
Subject: [PATCH] fix: NodeIterator return error from empty trie root

---
 trie/iterator.go      |  4 +++-
 trie/iterator_test.go | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/trie/iterator.go b/trie/iterator.go
index 26e8e48d4..b6003275f 100644
--- a/trie/iterator.go
+++ b/trie/iterator.go
@@ -940,7 +940,9 @@ func newMerkleTreeIterator(
 	it := &merkleTreeIterator{findNodeBlobByHash: findNodeBlobByHash, nodeBlobToIteratorNode: nodeBlobToIteratorNode}
 	var rootNode merkleTreeIteratorNode
 	var blob []byte
-	blob, it.err = findNodeBlobByHash(root)
+	if blob, it.err = findNodeBlobByHash(root); len(blob) == 0 {
+		return it
+	}
 	if it.err == nil {
 		rootNode, it.err = nodeBlobToIteratorNode(root, blob)
 	}
diff --git a/trie/iterator_test.go b/trie/iterator_test.go
index 8322904fc..d60d49ae0 100644
--- a/trie/iterator_test.go
+++ b/trie/iterator_test.go
@@ -661,6 +661,29 @@ func TestMerkleTreeIterator(t *testing.T) {
 		return tree, db
 	}
 
+	t.Run("empty root", func(t *testing.T) {
+		t.Run("zk merkle tree", func(t *testing.T) {
+			trie := NewEmptyMerkleTrie(NewZkDatabase(rawdb.NewMemoryDatabase()))
+			it, _ := trie.NodeIterator(nil)
+			for it.Next(true) {
+				t.Fail()
+			}
+			if it.Error() != nil {
+				t.Error(it.Error())
+			}
+		})
+		t.Run("zk trie", func(t *testing.T) {
+			trie, _ := NewZkTrie(common.Hash{}, NewZkDatabase(rawdb.NewDatabase(memorydb.New())))
+			it, _ := trie.NodeIterator(nil)
+			for it.Next(true) {
+				t.Fail()
+			}
+			if it.Error() != nil {
+				t.Error(it.Error())
+			}
+		})
+	})
+
 	t.Run("zk merkle tree", func(t *testing.T) {
 		tree, db := makeMerkleTreeWithData(testdata1)
 		expected := db.Len()