fix: trie should check if stem_state_write.writes is empty

portal-verkle-primitives/src/verkle/nodes/branch.rs

@@ -66,6 +66,10 @@ impl BranchNode {
     /// Returns by how much the commitmant hash has changed and the path to the new branch node if
     /// one was created.
     pub fn update(&mut self, state_write: &StemStateWrite) -> (ScalarField, NewBranchNode) {
+        if state_write.writes.is_empty() {
+            return (ScalarField::zero(), None);
+        }
+
         let index = state_write.stem[self.depth];
         let child = &mut self.children[index as usize];
         match child {

portal-verkle-primitives/src/verkle/trie.rs

@@ -51,7 +51,11 @@ impl VerkleTrie {
     pub fn update(&mut self, state_writes: &StateWrites) -> HashSet<TriePath> {
         let mut created_branches = HashSet::new();
         for stem_state_write in state_writes.iter() {
-            if let Some(created_branch) = self.root_node.update(stem_state_write).1 {
+            if stem_state_write.writes.is_empty() {
+                continue;
+            }
+            let (_, created_branch) = self.root_node.update(stem_state_write);
+            if let Some(created_branch) = created_branch {
                 created_branches.insert(created_branch);
             }
         }