`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.
{
    const std::string& walletFile = location.GetName();
    
    std::vector<CWalletTx> vWtx;
    if (gArgs.GetBoolArg("-zapwallettxes", false)) {
        uiInterface.InitMessage(_("Zapping all transactions from wallet..."));
        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(chain, location, WalletDatabase::Create(location.GetPath()));
        DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
        if (nZapWalletRet != DBErrors::LOAD_OK) {
            InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
            return nullptr;
        }
    }
    uiInterface.InitMessage(_("Loading wallet..."));
    int64_t nStart = GetTimeMillis();
    bool fFirstRun = true;