### 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_
bool IsSolvable() const final { return false; }
    std::optional<OutputType> GetOutputType() const override
    {
        CTxDestination dest;
        ExtractDestination(m_script, dest);
        return OutputTypeFromDestination(dest);
    }
    bool IsSingleType() const final { return true; }
    bool ToPrivateString(const SigningProvider& arg, std::string& out) const final { return false; }
};
class PKDescriptor final : public DescriptorImpl
{
private:
    const bool m_xonly;
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, Span<const CScript>, FlatSigningProvider&) const override
    {
        if (m_xonly) {
            CScript script = CScript() << ToByteVector(XOnlyPubKey(keys[0])) << OP_CHECKSIG;
            return Vector(std::move(script));
        } else {
            return Vector(GetScriptForRawPubKey(keys[0]));
        }
    }
public:
    PKDescriptor(std::unique_ptr<PubkeyProvider> prov, bool xonly = false) : DescriptorImpl(Vector(std::move(prov)), "pk"), m_xonly(xonly) {}
    bool IsSingleType() const final { return true; }
};
class PKHDescriptor final : public DescriptorImpl