### 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_
* Descriptors are strings that describe a set of scriptPubKeys, together with
 * all information necessary to solve them. By combining all information into
 * one, they avoid the need to separately import keys and scripts.
 *
 * Descriptors may be ranged, which occurs when the public keys inside are
 * specified in the form of HD chains (xpubs).
 *
 * Descriptors always represent public information - public keys and scripts -
 * but in cases where private keys need to be conveyed along with a descriptor,
 * they can be included inside by changing public keys to private keys (WIF
 * format), and changing xpubs by xprvs.
 *
 * Reference documentation about the descriptor language can be found in
 * doc/descriptors.md.
 */
struct Descriptor {
    virtual ~Descriptor() = default;
    
    virtual bool IsRange() const = 0;
    /** Whether this descriptor has all information about signing ignoring lack of private keys.
     *  This is true for all descriptors except ones that use `raw` or `addr` constructions. */
    virtual bool IsSolvable() const = 0;
    
    virtual std::string ToString() const = 0;
    
    virtual bool IsSingleType() const = 0;
    
    virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
    
    virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0;