### 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 (ctx == ParseScriptContext::TOP && Func("rawtr", expr)) {
        auto arg = Expr(expr);
        if (expr.size()) {
            error = strprintf("rawtr(): only one key expected.");
            return nullptr;
        }
        auto output_key = ParsePubkey(key_exp_index, arg, ParseScriptContext::P2TR, out, error);
        if (!output_key) return nullptr;
        ++key_exp_index;
        return std::make_unique<RawTRDescriptor>(std::move(output_key));
    } else if (Func("rawtr", expr)) {
        error = "Can only have rawtr at top level";
        return nullptr;
    }
    if (ctx == ParseScriptContext::TOP && Func("raw", expr)) {
        std::string str(expr.begin(), expr.end());
        if (!IsHex(str)) {
            error = "Raw script is not hex";
            return nullptr;
        }
        auto bytes = ParseHex(str);
        return std::make_unique<RawDescriptor>(CScript(bytes.begin(), bytes.end()));
    } else if (Func("raw", expr)) {
        error = "Can only have raw() at top level";
        return nullptr;
    }
    
    {
        KeyParser parser(&out, nullptr);
        auto node = miniscript::FromString(std::string(expr.begin(), expr.end()), parser);