### 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_
size_t GetSize() const override { return m_provider->GetSize(); }
    std::string ToString() const override { return "[" + OriginString() + "]" + m_provider->ToString(); }
    bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override
    {
        std::string sub;
        if (!m_provider->ToPrivateString(arg, sub)) return false;
        ret = "[" + OriginString() + "]" + std::move(sub);
        return true;
    }
    bool ToNormalizedString(const SigningProvider& arg, std::string& ret, const DescriptorCache* cache) const override
    {
        std::string sub;
        if (!m_provider->ToNormalizedString(arg, sub, cache)) return false;
        
        
        
        if (sub[0] == '[') {
            sub = sub.substr(9);
            ret = "[" + OriginString(true) + std::move(sub);
        } else {
            ret = "[" + OriginString(true) + "]" + std::move(sub);
        }
        return true;
    }
    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
    {
        return m_provider->GetPrivKey(pos, arg, key);
    }
};
class ConstPubkeyProvider final : public PubkeyProvider