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_KeyStore);
        if (fInternal) {
            setInternalKeyPool.insert(nIndex);
        } else if (!set_pre_split_keypool.empty()) {
            set_pre_split_keypool.insert(nIndex);
        } else {
            setExternalKeyPool.insert(nIndex);
        }
        CKeyID& pubkey_id = m_index_to_reserved_key.at(nIndex);
        m_pool_key_to_index[pubkey_id] = nIndex;
        m_index_to_reserved_key.erase(nIndex);
        NotifyCanGetAddressesChanged();
    }
    WalletLogPrintf("keypool return %d\n", nIndex);
}
bool LegacyScriptPubKeyMan::GetKeyFromPool(CPubKey& result, const OutputType type, bool internal)