### 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_
{
    LOCK(cs_desc_man);
    
    if (m_wallet_descriptor.next_index - 1 == index) {
        m_wallet_descriptor.next_index--;
    }
    WalletBatch(m_storage.GetDatabase()).WriteDescriptor(GetID(), m_wallet_descriptor);
    NotifyCanGetAddressesChanged();
}
std::map<CKeyID, CKey> DescriptorScriptPubKeyMan::GetKeys() const
{
    AssertLockHeld(cs_desc_man);
    if (m_storage.HasEncryptionKeys() && !m_storage.IsLocked()) {
        KeyMap keys;
        for (const auto& key_pair : m_map_crypted_keys) {
            const CPubKey& pubkey = key_pair.second.first;
            const std::vector<unsigned char>& crypted_secret = key_pair.second.second;
            CKey key;
            DecryptKey(m_storage.GetEncryptionKey(), crypted_secret, pubkey, key);
            keys[pubkey.GetID()] = key;
        }
        return keys;
    }
    return m_map_keys;
}
bool DescriptorScriptPubKeyMan::TopUp(unsigned int size)