`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.
entry.pushKV("category", "generate");
            }
            else
            {
                entry.pushKV("category", "receive");
            }
            entry.pushKV("amount", ValueFromAmount(r.amount));
            if (pwallet->mapAddressBook.count(r.destination)) {
                entry.pushKV("label", label);
            }
            entry.pushKV("vout", r.vout);
            if (fLong)
                WalletTxToJSON(pwallet->chain(), locked_chain, wtx, entry);
            ret.push_back(entry);
        }
    }
}
UniValue listtransactions(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() > 4)
        throw std::runtime_error(
            "listtransactions (dummy count skip include_watchonly)\n"
            "\nReturns up to 'count' most recent transactions skipping the first 'from' transactions.\n"
            "\nArguments:\n"
            "1. \"dummy\"    (string, optional) If set, should be \"*\" for backwards compatibility.\n"