I have 2 legacy wallets and on both if I run `upgradewallet` it will cause bitcoin core to crash. This should just return me an error string

Currenl result from `getwalletinfo`:
```
{
  "walletname": "Wallet",
  "walletversion": 169900,
  "format": "bdb",
  "balance": 0.00000000,
  "unconfirmed_balance": 0.00000000,
  "immature_balance": 0.00000000,
  "txcount": 80,
  "keypoololdest": 1613078825,
  "keypoolsize": 941,
  "keypoolsize_hd_internal": 941,
  "paytxfee": 0.00000000,
  "private_keys_enabled": false,
  "avoid_reuse": true,
  "scanning": false,
  "descriptors": false
}
```
{
    LOCK(cs_desc_man);
    
    if (m_wallet_descriptor.next_index - 1 == index) {
        m_wallet_descriptor.next_index--;
    }
    WalletBatch(m_storage.GetDatabase()).WriteDescriptor(GetID(), m_wallet_descriptor);
    NotifyCanGetAddressesChanged();
}
std::map<CKeyID, CKey> DescriptorScriptPubKeyMan::GetKeys() const
{
    AssertLockHeld(cs_desc_man);
    if (m_storage.HasEncryptionKeys() && !m_storage.IsLocked()) {
        KeyMap keys;
        for (auto key_pair : m_map_crypted_keys) {
            const CPubKey& pubkey = key_pair.second.first;
            const std::vector<unsigned char>& crypted_secret = key_pair.second.second;
            CKey key;
            DecryptKey(m_storage.GetEncryptionKey(), crypted_secret, pubkey, key);
            keys[pubkey.GetID()] = key;
        }
        return keys;
    }
    return m_map_keys;
}
bool DescriptorScriptPubKeyMan::TopUp(unsigned int size)