fn tree_node(&self, key: &NodeKey, is_leaf: bool) -> Option<Node> {
        self.try_tree_node(key, is_leaf)
            .unwrap_or_else(|err| panic!("{err}"))
    }
Obtains a node with the specified key from the tree storage.

# Panics

Panics on deserialization errors.
core/lib/merkle_tree/src/storage/database.rs