### 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_
final_extkey = xprv.Neuter();
            if (lh_xprv.key.IsValid()) {
                last_hardened_extkey = lh_xprv.Neuter();
            }
        } else {
            for (auto entry : m_path) {
                if (!parent_extkey.Derive(parent_extkey, entry)) return false;
            }
            final_extkey = parent_extkey;
            if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos);
            assert(m_derive != DeriveType::HARDENED);
        }
        if (!der) return false;
        final_info_out = final_info_out_tmp;
        key_out = final_extkey.pubkey;
        if (write_cache) {
            
            if (m_derive != DeriveType::HARDENED) {
                write_cache->CacheParentExtPubKey(m_expr_index, parent_extkey);
                
                if (last_hardened_extkey.pubkey.IsValid()) {
                    write_cache->CacheLastHardenedExtPubKey(m_expr_index, last_hardened_extkey);
                }
            } else if (final_info_out.path.size() > 0) {
                write_cache->CacheDerivedExtPubKey(m_expr_index, pos, final_extkey);
            }
        }
        return true;
    }
    std::string ToString(bool normalized) const