`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.
#include <qt/recentrequeststablemodel.h>
#include <qt/receiverequestdialog.h>
#include <memory>
#include <QAbstractButton>
#include <QAction>
#include <QApplication>
#include <QCheckBox>
#include <QPushButton>
#include <QTimer>
#include <QVBoxLayout>
#include <QTextEdit>
#include <QListView>
#include <QDialogButtonBox>
namespace
{
void ConfirmSend(QString* text = nullptr, bool cancel = false)
{
    QTimer::singleShot(0, [text, cancel]() {
        for (QWidget* widget : QApplication::topLevelWidgets()) {
            if (widget->inherits("SendConfirmationDialog")) {
                SendConfirmationDialog* dialog = qobject_cast<SendConfirmationDialog*>(widget);
                if (text) *text = dialog->text();
                QAbstractButton* button = dialog->button(cancel ? QMessageBox::Cancel : QMessageBox::Yes);
                button->setEnabled(true);
                button->click();
            }
        }
    });
}
uint256 SendCoins(CWallet& wallet, SendCoinsDialog& sendCoinsDialog, const CTxDestination& address, CAmount amount, bool rbf)