### 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_
RemoveWatchOnly(script);
    }
    m_storage.UnsetBlankWalletFlag(batch);
    if (!m_storage.HasEncryptionKeys()) {
        return batch.WriteKey(pubkey,
                                                 secret.GetPrivKey(),
                                                 mapKeyMetadata[pubkey.GetID()]);
    }
    return true;
}
bool LegacyScriptPubKeyMan::LoadCScript(const CScript& redeemScript)
{
    /* A sanity check was added in pull #3843 to avoid adding redeemScripts
     * that never can be redeemed. However, old wallets may still contain
     * these. Do not add them to the wallet and warn. */
    if (redeemScript.size() > MAX_SCRIPT_ELEMENT_SIZE)
    {
        std::string strAddr = EncodeDestination(ScriptHash(redeemScript));
        WalletLogPrintf("%s: Warning: This wallet contains a redeemScript of size %i which exceeds maximum size %i thus can never be redeemed. Do not use address %s.\n", __func__, redeemScript.size(), MAX_SCRIPT_ELEMENT_SIZE, strAddr);
        return true;
    }
    return FillableSigningProvider::AddCScript(redeemScript);
}
void LegacyScriptPubKeyMan::LoadKeyMetadata(const CKeyID& keyID, const CKeyMetadata& meta)
{
    LOCK(cs_KeyStore);
    UpdateTimeFirstKey(meta.nCreateTime);
    mapKeyMetadata[keyID] = meta;
}
void LegacyScriptPubKeyMan::LoadScriptMetadata(const CScriptID& script_id, const CKeyMetadata& meta)