fix(l1): remove "inconsistent internal tree structure" panics (#1288)

**Motivation**

The `Trie` library assumes that all tries are well-formed: this means
that if some node contains the hash of a child, then that child is in
the tire's database. If this doesn't hold, then a `get()` call panics
with an `inconsistent internal tree structure` message.

For the L2 prover we're using "pruned tries" which only store the
relevant nodes for the set of values touched in some execution, breaking
the previous hypothesis. One option was to capture the panics on the get
calls, but this wasn't safe because `Trie` has internal mutability. The
path chosen is to remove the panics altogether and replace them with
errors.

**Description**

- replaces mentioned panics for errors

crates/l2/prover/zkvm/interface/src/lib.rs

@@ -100,32 +100,45 @@ pub mod trie {
             } else {
                 // Add or update AccountState in the trie
                 // Fetch current state or create a new state to be inserted
-                let mut account_state = match state_trie.get(&hashed_address)? {
-                    Some(encoded_state) => AccountState::decode(&encoded_state)?,
-                    None => AccountState::default(),
+                let account_state = state_trie.get(&hashed_address);
+
+                // if there isn't a path into the account (inconsistent tree error), then
+                // it's potentially a new account. This is because we're using pruned tries
+                // so the path into a new account might not be included in the pruned state trie.
+                let mut account_state = match account_state {
+                    Ok(Some(encoded_state)) => AccountState::decode(&encoded_state)?,
+                    Ok(None) | Err(TrieError::InconsistentTree) => AccountState::default(),
+                    Err(err) => return Err(err.into()),
                 };
+                let is_account_new = account_state == AccountState::default();
+
                 if let Some(info) = &update.info {
                     account_state.nonce = info.nonce;
                     account_state.balance = info.balance;
                     account_state.code_hash = info.code_hash;
                 }
                 // Store the added storage in the account's storage trie and compute its new root
                 if !update.added_storage.is_empty() {
-                    let storage_trie = storage_tries
-                        .get_mut(&update.address)
-                        .ok_or(Error::StorageNotFound(update.address))?;
+                    let storage_trie = if is_account_new {
+                        let trie = Trie::from_nodes(None, &[])?;
+                        storage_tries.insert(update.address, trie);
+                        storage_tries.get_mut(&update.address).unwrap()
+                    } else {
+                        storage_tries
+                            .get_mut(&update.address)
+                            .ok_or(Error::StorageNotFound(update.address))?
+                    };
                     for (storage_key, storage_value) in &update.added_storage {
                         let hashed_key = hash_key(storage_key);
-                        if storage_value.is_zero() {
+                        if storage_value.is_zero() && !is_account_new {
                             storage_trie.remove(hashed_key)?;
-                        } else {
+                        } else if !storage_value.is_zero() {
                             storage_trie.insert(hashed_key, storage_value.encode_to_vec())?;
                         }
                     }
                     account_state.storage_root = storage_trie.hash_no_commit();
                 }
                 state_trie.insert(hashed_address, account_state.encode_to_vec())?;
-                println!("inserted new state");
             }
         }
         Ok(())

crates/storage/trie/error.rs

@@ -9,4 +9,6 @@ pub enum TrieError {
     RLPDecode(#[from] RLPDecodeError),
     #[error("Verification Error: {0}")]
     Verify(String),
+    #[error("Inconsistent internal tree structure")]
+    InconsistentTree,
 }

crates/storage/trie/node/branch.rs

@@ -62,7 +62,7 @@ impl BranchNode {
             if child_hash.is_valid() {
                 let child_node = state
                     .get_node(child_hash.clone())?
-                    .expect("inconsistent internal tree structure");
+                    .ok_or(TrieError::InconsistentTree)?;
                 child_node.get(state, path)
             } else {
                 Ok(None)
@@ -94,7 +94,7 @@ impl BranchNode {
                 choice_hash => {
                     let child_node = state
                         .get_node(choice_hash.clone())?
-                        .expect("inconsistent internal tree structure");
+                        .ok_or(TrieError::InconsistentTree)?;
 
                     let child_node = child_node.insert(state, path, value)?;
                     *choice_hash = child_node.insert_self(state)?;
@@ -139,7 +139,7 @@ impl BranchNode {
             if self.choices[choice_index].is_valid() {
                 let child_node = state
                     .get_node(self.choices[choice_index].clone())?
-                    .expect("inconsistent internal tree structure");
+                    .ok_or(TrieError::InconsistentTree)?;
                 // Remove value from child node
                 let (child_node, old_value) = child_node.remove(state, path.clone())?;
                 if let Some(child_node) = child_node {
@@ -180,7 +180,7 @@ impl BranchNode {
                 let (choice_index, child_hash) = children[0];
                 let child = state
                     .get_node(child_hash.clone())?
-                    .expect("inconsistent internal tree structure");
+                    .ok_or(TrieError::InconsistentTree)?;
                 match child {
                     // Replace self with an extension node leading to the child
                     Node::Branch(_) => ExtensionNode::new(
@@ -254,7 +254,7 @@ impl BranchNode {
             if child_hash.is_valid() {
                 let child_node = state
                     .get_node(child_hash.clone())?
-                    .expect("inconsistent internal tree structure");
+                    .ok_or(TrieError::InconsistentTree)?;
                 child_node.get_path(state, path, node_path)?;
             }
         }

crates/storage/trie/node/extension.rs

@@ -29,7 +29,7 @@ impl ExtensionNode {
         if path.skip_prefix(&self.prefix) {
             let child_node = state
                 .get_node(self.child.clone())?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
 
             child_node.get(state, path)
         } else {
@@ -59,7 +59,7 @@ impl ExtensionNode {
             // Insert into child node
             let child_node = state
                 .get_node(self.child)?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
             let new_child_node =
                 child_node.insert(state, path.offset(match_index), value.clone())?;
             self.child = new_child_node.insert_self(state)?;
@@ -76,7 +76,7 @@ impl ExtensionNode {
                     Some(Node::Leaf(leaf)) => {
                         BranchNode::new_with_value(Box::new(choices), leaf.value)
                     }
-                    _ => panic!("inconsistent internal tree structure"),
+                    _ => return Err(TrieError::InconsistentTree),
                 }
             } else {
                 choices[self.prefix.at(0)] = new_node;
@@ -109,7 +109,7 @@ impl ExtensionNode {
         if path.skip_prefix(&self.prefix) {
             let child_node = state
                 .get_node(self.child)?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
             // Remove value from child subtrie
             let (child_node, old_value) = child_node.remove(state, path)?;
             // Restructure node based on removal
@@ -189,7 +189,7 @@ impl ExtensionNode {
         if path.skip_prefix(&self.prefix) {
             let child_node = state
                 .get_node(self.child.clone())?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
             child_node.get_path(state, path, node_path)?;
         }
         Ok(())

crates/storage/trie/trie.rs

@@ -77,7 +77,7 @@ impl Trie {
             let root_node = self
                 .state
                 .get_node(root.clone())?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
             root_node.get(&self.state, Nibbles::from_bytes(path))
         } else {
             Ok(None)
@@ -112,7 +112,7 @@ impl Trie {
             let root_node = self
                 .state
                 .get_node(root)?
-                .expect("inconsistent internal tree structure");
+                .ok_or(TrieError::InconsistentTree)?;
             let (root_node, old_value) =
                 root_node.remove(&mut self.state, Nibbles::from_bytes(&path))?;
             self.root = root_node
@@ -291,7 +291,7 @@ impl Trie {
                         let child_node = self
                             .state
                             .get_node(child_hash.clone())?
-                            .expect("inconsistent internal tree structure");
+                            .ok_or(TrieError::InconsistentTree)?;
                         self.get_node_inner(child_node, partial_path)
                     } else {
                         Ok(vec![])
@@ -306,7 +306,7 @@ impl Trie {
                     let child_node = self
                         .state
                         .get_node(extension_node.child.clone())?
-                        .expect("inconsistent internal tree structure");
+                        .ok_or(TrieError::InconsistentTree)?;
                     self.get_node_inner(child_node, partial_path)
                 } else {
                     Ok(vec![])