`ScanForWalletTransactions()` has the following comment about its return value:

```
 * Returns null if scan was successful. Otherwise, if a complete rescan was not
 * possible (due to pruning or corruption), returns pointer to the most recent
 * block that could not be scanned.
```

This is not strictly true. If `abortrescan` is called, then `ScanForWalletTransactions()` will return `nullptr`, even though the scan wasn't successful to the tip.

This in turn causes a minor bug in `importmulti`, where the call doesn't return the correct error and warning about potentially not finding transactions if `abortrescan` was called.

I think the correct fix is for `ScanForWalletTransactions()` to inform the caller that the rescan was aborted.
{
    auto locked_chain = chain().lock();
    LOCK(cs_wallet);
    fFirstRunRet = false;
    DBErrors nLoadWalletRet = WalletBatch(*database,"cr+").LoadWallet(this);
    if (nLoadWalletRet == DBErrors::NEED_REWRITE)
    {
        if (database->Rewrite("\x04pool"))
        {
            setInternalKeyPool.clear();
            setExternalKeyPool.clear();
            m_pool_key_to_index.clear();
            
            
            
        }
    }
    {
        LOCK(cs_KeyStore);
        
        fFirstRunRet = mapKeys.empty() && mapCryptedKeys.empty() && mapWatchKeys.empty() && setWatchOnly.empty() && mapScripts.empty() && !IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
    }
    if (nLoadWalletRet != DBErrors::LOAD_OK)
        return nLoadWalletRet;
    return DBErrors::LOAD_OK;
}
DBErrors CWallet::ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut)