### 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_
{
        std::string ret;
        ToStringHelper(nullptr, ret, StringType::PUBLIC);
        return AddChecksum(ret);
    }
    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
    {
        bool ret = ToStringHelper(&arg, out, StringType::PRIVATE);
        out = AddChecksum(out);
        return ret;
    }
    bool ToNormalizedString(const SigningProvider& arg, std::string& out, const DescriptorCache* cache) const override final
    {
        bool ret = ToStringHelper(&arg, out, StringType::NORMALIZED, cache);
        out = AddChecksum(out);
        return ret;
    }
    bool ExpandHelper(int pos, const SigningProvider& arg, const DescriptorCache* read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache) const