### 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);
    assert(m_max_keypool_index < std::numeric_limits<int64_t>::max()); 
    int64_t index = ++m_max_keypool_index;
    if (!batch.WritePool(index, CKeyPool(pubkey, internal))) {
        throw std::runtime_error(std::string(__func__) + ": writing imported pubkey failed");
    }
    if (internal) {
        setInternalKeyPool.insert(index);
    } else {
        setExternalKeyPool.insert(index);
    }
    m_pool_key_to_index[pubkey.GetID()] = index;
}
void LegacyScriptPubKeyMan::KeepDestination(int64_t nIndex, const OutputType& type)
{
    assert(type != OutputType::BECH32M);
    
    WalletBatch batch(m_storage.GetDatabase());
    batch.ErasePool(nIndex);
    CPubKey pubkey;
    bool have_pk = GetPubKey(m_index_to_reserved_key.at(nIndex), pubkey);
    assert(have_pk);
    LearnRelatedScripts(pubkey, type);
    m_index_to_reserved_key.erase(nIndex);
    WalletLogPrintf("keypool keep %d\n", nIndex);
}
void LegacyScriptPubKeyMan::ReturnDestination(int64_t nIndex, bool fInternal, const CTxDestination&)