### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current behaviour

crash

### Expected behaviour

no crash

### Steps to reproduce

* Compile 79e8247ddb166f9b980f40249b7372a502402a4d
* Type `migratewallet`

### Relevant log output

```
wallet/scriptpubkeyman.cpp:1915: std::optional<MigrationData> wallet::LegacyScriptPubKeyMan::MigrateToDescriptor(): Assertion `IsMine(desc_spk) != ISMINE_NO' failed.
Aborted (core dumped)
```


### How did you obtain Bitcoin Core

Compiled from source

### What version of Bitcoin Core are you using?

current master

### Operating system and version

Linux

### Machine specifications

_No response_
{
    std::unique_ptr<FlatSigningProvider> keys = std::make_unique<FlatSigningProvider>();
    for (const auto& coin_pair : coins) {
        std::unique_ptr<FlatSigningProvider> coin_keys = GetSigningProvider(coin_pair.second.out.scriptPubKey, true);
        if (!coin_keys) {
            continue;
        }
        keys->Merge(std::move(*coin_keys));
    }
    return ::SignTransaction(tx, keys.get(), coins, sighash, input_errors);
}
SigningResult DescriptorScriptPubKeyMan::SignMessage(const std::string& message, const PKHash& pkhash, std::string& str_sig) const
{
    std::unique_ptr<FlatSigningProvider> keys = GetSigningProvider(GetScriptForDestination(pkhash), true);
    if (!keys) {
        return SigningResult::PRIVATE_KEY_NOT_AVAILABLE;
    }
    CKey key;
    if (!keys->GetKey(ToKeyID(pkhash), key)) {
        return SigningResult::PRIVATE_KEY_NOT_AVAILABLE;
    }
    if (!MessageSign(key, message, str_sig)) {
        return SigningResult::SIGNING_FAILED;
    }
    return SigningResult::OK;
}
TransactionError DescriptorScriptPubKeyMan::FillPSBT(PartiallySignedTransaction& psbtx, const PrecomputedTransactionData& txdata, int sighash_type, bool sign, bool bip32derivs, int* n_signed, bool finalize) const