### 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_
{
    CDataStream s(0, 0);
    SerializeMany(s, args...);
    return {s.begin(), s.end()};
}
BOOST_FIXTURE_TEST_CASE(wallet_load_ckey, TestingSetup)
{
    SerializeData ckey_record_key;
    SerializeData ckey_record_value;
    MockableData records;
    {
        
        
        std::shared_ptr<CWallet> wallet(new CWallet(m_node.chain.get(), "", CreateMockableWalletDatabase()));
        LOCK(wallet->cs_wallet);
        auto legacy_spkm = wallet->GetOrCreateLegacyScriptPubKeyMan();
        BOOST_CHECK(legacy_spkm->SetupGeneration(true));
        
        CTxDestination dest = *Assert(legacy_spkm->GetNewDestination(OutputType::LEGACY));
        CKeyID key_id = GetKeyForDestination(*legacy_spkm, dest);
        CKey first_key;
        BOOST_CHECK(legacy_spkm->GetKey(key_id, first_key));
        
        BOOST_CHECK(wallet->EncryptWallet("encrypt"));
        wallet->Flush();
        
        records = GetMockableDatabase(*wallet).m_records;
        
        ckey_record_key = MakeSerializeData(DBKeys::CRYPTED_KEY, first_key.GetPubKey());