### 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_
{
    if (!WriteIC(std::make_pair(DBKeys::WALLETDESCRIPTORCKEY, std::make_pair(desc_id, pubkey)), secret, false)) {
        return false;
    }
    EraseIC(std::make_pair(DBKeys::WALLETDESCRIPTORKEY, std::make_pair(desc_id, pubkey)));
    return true;
}
bool WalletBatch::WriteDescriptor(const uint256& desc_id, const WalletDescriptor& descriptor)
{
    return WriteIC(make_pair(DBKeys::WALLETDESCRIPTOR, desc_id), descriptor);
}
bool WalletBatch::WriteDescriptorDerivedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index, uint32_t der_index)
{
    std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
    xpub.Encode(ser_xpub.data());
    return WriteIC(std::make_pair(std::make_pair(DBKeys::WALLETDESCRIPTORCACHE, desc_id), std::make_pair(key_exp_index, der_index)), ser_xpub);
}
bool WalletBatch::WriteDescriptorParentCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index)
{
    std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
    xpub.Encode(ser_xpub.data());
    return WriteIC(std::make_pair(std::make_pair(DBKeys::WALLETDESCRIPTORCACHE, desc_id), key_exp_index), ser_xpub);
}
bool WalletBatch::WriteDescriptorLastHardenedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index)
{
    std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
    xpub.Encode(ser_xpub.data());
    return WriteIC(std::make_pair(std::make_pair(DBKeys::WALLETDESCRIPTORLHCACHE, desc_id), key_exp_index), ser_xpub);
}
bool WalletBatch::WriteDescriptorCacheItems(const uint256& desc_id, const DescriptorCache& cache)