### 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_res.m_result);
        num_keys = key_res.m_records;
        
        prefix = PrefixStream(DBKeys::WALLETDESCRIPTORCKEY, id);
        LoadResult ckey_res = LoadRecords(pwallet, batch, DBKeys::WALLETDESCRIPTORCKEY, prefix,
            [&id, &spk_man] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
            uint256 desc_id;
            CPubKey pubkey;
            key >> desc_id;
            assert(desc_id == id);
            key >> pubkey;
            if (!pubkey.IsValid())
            {
                err = "Error reading wallet database: descriptor encrypted key CPubKey corrupt";
                return DBErrors::CORRUPT;
            }
            std::vector<unsigned char> privkey;
            value >> privkey;
            spk_man->AddCryptedKey(pubkey.GetID(), pubkey, privkey);
            return DBErrors::LOAD_OK;
        });
        result = std::max(result, ckey_res.m_result);
        num_ckeys = ckey_res.m_records;
        return result;
    });
    if (desc_res.m_result <= DBErrors::NONCRITICAL_ERROR) {
        
        pwallet->WalletLogPrintf("Descriptors: %u, Descriptor Keys: %u plaintext, %u encrypted, %u total.\n",