`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.
{
        CMutableTransaction tx1 {*this->tx};
        CMutableTransaction tx2 {*_tx.tx};
        for (auto& txin : tx1.vin) txin.scriptSig = CScript();
        for (auto& txin : tx2.vin) txin.scriptSig = CScript();
        return CTransaction(tx1) == CTransaction(tx2);
}
std::vector<uint256> CWallet::ResendWalletTransactionsBefore(interfaces::Chain::Lock& locked_chain, int64_t nTime, CConnman* connman)
{
    std::vector<uint256> result;
    LOCK(cs_wallet);
    
    std::multimap<unsigned int, CWalletTx*> mapSorted;
    for (std::pair<const uint256, CWalletTx>& item : mapWallet)
    {
        CWalletTx& wtx = item.second;
        
        if (wtx.nTimeReceived > nTime)
            continue;
        mapSorted.insert(std::make_pair(wtx.nTimeReceived, &wtx));
    }
    for (const std::pair<const unsigned int, CWalletTx*>& item : mapSorted)
    {
        CWalletTx& wtx = *item.second;
        if (wtx.RelayWalletTransaction(locked_chain, connman))
            result.push_back(wtx.GetHash());
    }
    return result;
}
void CWallet::ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman)