### 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_
DatabaseCursor::Status status = cursor->Next(key, value);
            if (status != DatabaseCursor::Status::DONE) {
                pwallet->WalletLogPrintf("Error: Unexpected legacy entry found in descriptor wallet %s. The wallet might have been tampered with or created with malicious intent.\n", pwallet->GetName());
                return DBErrors::UNEXPECTED_LEGACY_ENTRY;
            }
        }
        return DBErrors::LOAD_OK;
    }
    
    
    LoadResult hd_chain_res = LoadRecords(pwallet, batch, DBKeys::HDCHAIN,
        [] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
        return LoadHDChain(pwallet, value, err) ? DBErrors:: LOAD_OK : DBErrors::CORRUPT;
    });
    result = std::max(result, hd_chain_res.m_result);
    
    LoadResult key_res = LoadRecords(pwallet, batch, DBKeys::KEY,
        [] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
        return LoadKey(pwallet, key, value, err) ? DBErrors::LOAD_OK : DBErrors::CORRUPT;
    });
    result = std::max(result, key_res.m_result);
    
    LoadResult ckey_res = LoadRecords(pwallet, batch, DBKeys::CRYPTED_KEY,
        [] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& err) {
        return LoadCryptedKey(pwallet, key, value, err) ? DBErrors::LOAD_OK : DBErrors::CORRUPT;
    });
    result = std::max(result, ckey_res.m_result);
    
    LoadResult script_res = LoadRecords(pwallet, batch, DBKeys::CSCRIPT,
        [] (CWallet* pwallet, DataStream& key, CDataStream& value, std::string& strErr) {