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
}
```
{
    switch (IsMineInner(*this, script, IsMineSigVersion::TOP)) {
    case IsMineResult::INVALID:
    case IsMineResult::NO:
        return ISMINE_NO;
    case IsMineResult::WATCH_ONLY:
        return ISMINE_WATCH_ONLY;
    case IsMineResult::SPENDABLE:
        return ISMINE_SPENDABLE;
    }
    assert(false);
}
bool LegacyScriptPubKeyMan::CheckDecryptionKey(const CKeyingMaterial& master_key, bool accept_no_keys)
{
    {
        LOCK(cs_KeyStore);
        assert(mapKeys.empty());
        bool keyPass = mapCryptedKeys.empty(); 
        bool keyFail = false;
        CryptedKeyMap::const_iterator mi = mapCryptedKeys.begin();
        WalletBatch batch(m_storage.GetDatabase());