### 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 std::make_unique<LegacySigningProvider>(*this);
}
bool LegacyScriptPubKeyMan::CanProvide(const CScript& script, SignatureData& sigdata)
{
    IsMineResult ismine = IsMineInner(*this, script, IsMineSigVersion::TOP,  false);
    if (ismine == IsMineResult::SPENDABLE || ismine == IsMineResult::WATCH_ONLY) {
        
        
        
        return true;
    } else {
        
        ProduceSignature(*this, DUMMY_SIGNATURE_CREATOR, script, sigdata);
        if (!sigdata.signatures.empty()) {
            
            bool has_privkeys = false;
            for (const auto& key_sig_pair : sigdata.signatures) {
                has_privkeys |= HaveKey(key_sig_pair.first);
            }
            return has_privkeys;
        }
        return false;
    }
}
bool LegacyScriptPubKeyMan::SignTransaction(CMutableTransaction& tx, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, bilingual_str>& input_errors) const