### 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 DBErrors::UNKNOWN_DESCRIPTOR;
        }
        pwallet->LoadDescriptorScriptPubKeyMan(id, desc);
        DescriptorCache cache;
        
        DataStream prefix = PrefixStream(DBKeys::WALLETDESCRIPTORCACHE, id);
        LoadResult key_cache_res = LoadRecords(pwallet, batch, DBKeys::WALLETDESCRIPTORCACHE, prefix,
            [&id, &cache] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
            bool parent = true;
            uint256 desc_id;
            uint32_t key_exp_index;
            uint32_t der_index;
            key >> desc_id;
            assert(desc_id == id);
            key >> key_exp_index;
            
            try
            {
                key >> der_index;
                parent = false;
            }
            catch (...) {}
            std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
            value >> ser_xpub;
            CExtPubKey xpub;
            xpub.Decode(ser_xpub.data());
            if (parent) {
                cache.CacheParentExtPubKey(key_exp_index, xpub);
            } else {
                cache.CacheDerivedExtPubKey(key_exp_index, der_index, xpub);