### 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_
CPubKey pubkey;
            key >> desc_id;
            assert(desc_id == id);
            key >> pubkey;
            if (!pubkey.IsValid())
            {
                strErr = "Error reading wallet database: descriptor unencrypted key CPubKey corrupt";
                return DBErrors::CORRUPT;
            }
            CKey privkey;
            CPrivKey pkey;
            uint256 hash;
            value >> pkey;
            value >> hash;
            
            std::vector<unsigned char> to_hash;
            to_hash.reserve(pubkey.size() + pkey.size());
            to_hash.insert(to_hash.end(), pubkey.begin(), pubkey.end());
            to_hash.insert(to_hash.end(), pkey.begin(), pkey.end());
            if (Hash(to_hash) != hash)
            {
                strErr = "Error reading wallet database: descriptor unencrypted key CPubKey/CPrivKey corrupt";
                return DBErrors::CORRUPT;
            }
            if (!privkey.Load(pkey, pubkey, true))
            {
                strErr = "Error reading wallet database: descriptor unencrypted key CPrivKey corrupt";
                return DBErrors::CORRUPT;
            }
            spk_man->AddKey(pubkey.GetID(), privkey);