https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=56270
const std::vector<unsigned char> data;
    
    const std::vector<NodeRef<Key>> subs;
private:
    
    const internal::Ops ops;
    
    const internal::StackSize ss;
    
    const Type typ;
    
    const size_t scriptlen;
    
    
    
    
    
    mutable std::optional<bool> has_duplicate_keys;
    
    size_t CalcScriptLen() const {
        size_t subsize = 0;
        for (const auto& sub : subs) {
            subsize += sub->ScriptSize();
        }
        Type sub0type = subs.size() > 0 ? subs[0]->GetType() : ""_mst;
        return internal::ComputeScriptLen(fragment, sub0type, subsize, k, subs.size(), keys.size());
    }
    /* Apply a recursive algorithm to a Miniscript tree, without actual recursive calls.
     *
     * The algorithm is defined by two functions: downfn and upfn. Conceptually, the