### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current behaviour

I randomly encountered this by loading a wallet created from master with an older version. I could trace it down to bd13dc2f46ea10302a928fcf0f53b7aed77ad260 (#26076), but I don't know descriptor wallets enough to understand what's going on (cc @Sjors @achow101).

### Expected behaviour

`bitcoind` starts, or at least tells me to use a later version if #26076 was a breaking change instead of corrupting `wallet.dat`.

### Steps to reproduce

(master, clean chain): 
`createwallet -regtest ""`
(v25.0rc2):
first `bitcoind -regtest` succeeds
then stop and restart the node: The second `bitcoind -regtest` leads to an InitError:
`Error: Error: Unable to expand wallet descriptor from cache`
now, the wallet cannot be loaded by either version.

### Relevant log output

_No response_

### How did you obtain Bitcoin Core

Compiled from source

### What version of Bitcoin Core are you using?

v25.0rc2 / master

### Operating system and version

Ubuntu

### Machine specifications

_No response_
{
    LOCK(cs_KeyStore);
    encrypted_batch = batch;
    if (!mapCryptedKeys.empty()) {
        encrypted_batch = nullptr;
        return false;
    }
    KeyMap keys_to_encrypt;
    keys_to_encrypt.swap(mapKeys); 
    for (const KeyMap::value_type& mKey : keys_to_encrypt)
    {
        const CKey &key = mKey.second;
        CPubKey vchPubKey = key.GetPubKey();
        CKeyingMaterial vchSecret(key.begin(), key.end());
        std::vector<unsigned char> vchCryptedSecret;
        if (!EncryptSecret(master_key, vchSecret, vchPubKey.GetHash(), vchCryptedSecret)) {
            encrypted_batch = nullptr;
            return false;
        }
        if (!AddCryptedKey(vchPubKey, vchCryptedSecret)) {
            encrypted_batch = nullptr;
            return false;
        }
    }
    encrypted_batch = nullptr;
    return true;
}
util::Result<CTxDestination> LegacyScriptPubKeyMan::GetReservedDestination(const OutputType type, bool internal, int64_t& index, CKeyPool& keypool)