`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.
{
    QTableView* table = view.findChild<QTableView*>("transactionView");
    QModelIndex index = FindTx(*table->selectionModel()->model(), txid);
    QVERIFY2(index.isValid(), "Could not find BumpFee txid");
    
    
    QAction* action = view.findChild<QAction*>("bumpFeeAction");
    table->selectionModel()->select(index, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
    action->setEnabled(expectDisabled);
    table->customContextMenuRequested({});
    QCOMPARE(action->isEnabled(), !expectDisabled);
    action->setEnabled(true);
    QString text;
    if (expectError.empty()) {
        ConfirmSend(&text, cancel);
    } else {
        ConfirmMessage(&text);
    }
    action->trigger();
    QVERIFY(text.indexOf(QString::fromStdString(expectError)) != -1);
}
void TestGUI()