`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.
ReceiveRequestDialog* receiveRequestDialog = qobject_cast<ReceiveRequestDialog*>(widget);
            QTextEdit* rlist = receiveRequestDialog->QObject::findChild<QTextEdit*>("outUri");
            QString paymentText = rlist->toPlainText();
            QStringList paymentTextList = paymentText.split('\n');
            QCOMPARE(paymentTextList.at(0), QString("Payment information"));
            QVERIFY(paymentTextList.at(1).indexOf(QString("URI: bitcoin:")) != -1);
            QVERIFY(paymentTextList.at(2).indexOf(QString("Address:")) != -1);
            QCOMPARE(paymentTextList.at(3), QString("Amount: 0.00000001 ") + QString::fromStdString(CURRENCY_UNIT));
            QCOMPARE(paymentTextList.at(4), QString("Label: TEST_LABEL_1"));
            QCOMPARE(paymentTextList.at(5), QString("Message: TEST_MESSAGE_1"));
        }
    }
    
    QPushButton* clearButton = receiveCoinsDialog.findChild<QPushButton*>("clearButton");
    clearButton->click();
    QCOMPARE(labelInput->text(), QString(""));
    QCOMPARE(amountInput->value(), CAmount(0));
    QCOMPARE(messageInput->text(), QString(""));
    
    int currentRowCount = requestTableModel->rowCount({});
    QCOMPARE(currentRowCount, initialRowCount+1);
    
    QTableView* table = receiveCoinsDialog.findChild<QTableView*>("recentRequestsView");
    table->selectRow(currentRowCount-1);
    QPushButton* removeRequestButton = receiveCoinsDialog.findChild<QPushButton*>("removeRequestButton");
    removeRequestButton->click();
    QCOMPARE(requestTableModel->rowCount({}), currentRowCount-1);
}
} 
void WalletTests::walletTests()