### 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_
}
            return DBErrors::LOAD_OK;
        });
        result = std::max(result, key_cache_res.m_result);
        
        prefix = PrefixStream(DBKeys::WALLETDESCRIPTORLHCACHE, id);
        LoadResult lh_cache_res = LoadRecords(pwallet, batch, DBKeys::WALLETDESCRIPTORLHCACHE, prefix,
            [&id, &cache] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
            uint256 desc_id;
            uint32_t key_exp_index;
            key >> desc_id;
            assert(desc_id == id);
            key >> key_exp_index;
            std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
            value >> ser_xpub;
            CExtPubKey xpub;
            xpub.Decode(ser_xpub.data());
            cache.CacheLastHardenedExtPubKey(key_exp_index, xpub);
            return DBErrors::LOAD_OK;
        });
        result = std::max(result, lh_cache_res.m_result);
        
        auto spk_man = (DescriptorScriptPubKeyMan*)pwallet->GetScriptPubKeyMan(id);
        assert(spk_man);
        spk_man->SetCache(cache);
        
        prefix = PrefixStream(DBKeys::WALLETDESCRIPTORKEY, id);
        LoadResult key_res = LoadRecords(pwallet, batch, DBKeys::WALLETDESCRIPTORKEY, prefix,
            [&id, &spk_man] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& strErr) {
            uint256 desc_id;