@achow101 noted we don't reject them therefore they must be silently accepted. This is not part of the specs, we should remove them. Also cc @sipa.

I can take care of this.
{
        if (!GetExtKey(arg, xprv)) return false;
        for (auto entry : m_path) {
            if (!xprv.Derive(xprv, entry)) return false;
            if (entry >> 31) {
                last_hardened = xprv;
            }
        }
        return true;
    }
    bool IsHardened() const
    {
        if (m_derive == DeriveType::HARDENED) return true;
        for (auto entry : m_path) {
            if (entry >> 31) return true;
        }
        return false;
    }
public:
    BIP32PubkeyProvider(uint32_t exp_index, const CExtPubKey& extkey, KeyPath path, DeriveType derive, bool apostrophe) : PubkeyProvider(exp_index), m_root_extkey(extkey), m_path(std::move(path)), m_derive(derive), m_apostrophe(apostrophe) {}
    bool IsRange() const override { return m_derive != DeriveType::NO; }
    size_t GetSize() const override { return 33; }
    bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key_out, KeyOriginInfo& final_info_out, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const override