### 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 (script_size + 3 > MAX_SCRIPT_ELEMENT_SIZE) {
                error = strprintf("P2SH script is too large, %d bytes is larger than %d bytes", script_size + 3, MAX_SCRIPT_ELEMENT_SIZE);
                return nullptr;
            }
        }
        if (multi || sortedmulti) {
            return std::make_unique<MultisigDescriptor>(thres, std::move(providers), sortedmulti);
        } else {
            return std::make_unique<MultiADescriptor>(thres, std::move(providers), sortedmulti_a);
        }
    } else if (multi || sortedmulti) {
        error = "Can only have multi/sortedmulti at top level, in sh(), or in wsh()";
        return nullptr;
    } else if (multi_a || sortedmulti_a) {
        error = "Can only have multi_a/sortedmulti_a inside tr()";
        return nullptr;
    }
    if ((ctx == ParseScriptContext::TOP || ctx == ParseScriptContext::P2SH) && Func("wpkh", expr)) {
        auto pubkey = ParsePubkey(key_exp_index, expr, ParseScriptContext::P2WPKH, out, error);
        if (!pubkey) {
            error = strprintf("wpkh(): %s", error);
            return nullptr;
        }
        key_exp_index++;
        return std::make_unique<WPKHDescriptor>(std::move(pubkey));
    } else if (Func("wpkh", expr)) {
        error = "Can only have wpkh() at top level or inside sh()";
        return nullptr;
    }
    if (ctx == ParseScriptContext::TOP && Func("sh", expr)) {