### 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_
{
    LOCK(cs_KeyStore);
    WalletBatch batch(m_storage.GetDatabase());
    return LegacyScriptPubKeyMan::AddKeyPubKeyWithDB(batch, secret, pubkey);
}
bool LegacyScriptPubKeyMan::AddKeyPubKeyWithDB(WalletBatch& batch, const CKey& secret, const CPubKey& pubkey)
{
    AssertLockHeld(cs_KeyStore);
    
    assert(!m_storage.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
    
    
    
    bool needsDB = !encrypted_batch;
    if (needsDB) {
        encrypted_batch = &batch;
    }
    if (!AddKeyPubKeyInner(secret, pubkey)) {
        if (needsDB) encrypted_batch = nullptr;
        return false;
    }
    if (needsDB) encrypted_batch = nullptr;
    
    CScript script;
    script = GetScriptForDestination(PKHash(pubkey));
    if (HaveWatchOnly(script)) {
        RemoveWatchOnly(script);
    }
    script = GetScriptForRawPubKey(pubkey);
    if (HaveWatchOnly(script)) {