### 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_
CacheDerivedExtPubKey(derived_xpub_map_pair.first, derived_xpub_pair.first, derived_xpub_pair.second);
            diff.CacheDerivedExtPubKey(derived_xpub_map_pair.first, derived_xpub_pair.first, derived_xpub_pair.second);
        }
    }
    for (const auto& lh_xpub_pair : other.GetCachedLastHardenedExtPubKeys()) {
        CExtPubKey xpub;
        if (GetCachedLastHardenedExtPubKey(lh_xpub_pair.first, xpub)) {
            if (xpub != lh_xpub_pair.second) {
                throw std::runtime_error(std::string(__func__) + ": New cached last hardened xpub does not match already cached last hardened xpub");
            }
            continue;
        }
        CacheLastHardenedExtPubKey(lh_xpub_pair.first, lh_xpub_pair.second);
        diff.CacheLastHardenedExtPubKey(lh_xpub_pair.first, lh_xpub_pair.second);
    }
    return diff;
}
ExtPubKeyMap DescriptorCache::GetCachedParentExtPubKeys() const
{
    return m_parent_xpubs;
}
std::unordered_map<uint32_t, ExtPubKeyMap> DescriptorCache::GetCachedDerivedExtPubKeys() const
{
    return m_derived_xpubs;
}
ExtPubKeyMap DescriptorCache::GetCachedLastHardenedExtPubKeys() const
{
    return m_last_hardened_xpubs;
}