Is this a bug that we cannot rely on activeSubWindow returning a pointer to the active subwindow?

void MdiWindow::fileNew()
{
    DocumentWindow *document = new DocumentWindow();
    QMdiSubWindow *subWindow = workspace->addSubWindow(document);
    workspace->setActiveSubWindow(subWindow);
    connect(document, &DocumentWindow::copyAvailable, this, &MdiWindow::updateEditActions);

    // create action for this submenu item
    // QString text = tr("&%1 %2").arg(orderedSubWindows.size() + 1).arg(document->windowTitle());

   // QString text = document->getName();;
    QAction *action = new QAction("", this);
    action->setCheckable(true);
    connect(action, &QAction::triggered, this, [this, subWindow]() {
        workspace->setActiveSubWindow(subWindow);
    });
    windowActions[subWindow] = action;
    orderedSubWindows.append(subWindow);

    // connect(subWindow, &QObject::destroyed, this, [this, subWindow]() {
    //     windowActions.remove(subWindow);
    //     orderedSubWindows.removeOne(subWindow);
    //     updateWindowMenu();  // Update menu when a subwindow is destroyed
    // });

    document->show();
    //subWindow->show();
   // workspace->setActiveSubWindow(subWindow);
    enableActions();

    qDebug() << "After setActiveSubWindow:";
    qDebug() << "  Active subwindow:" << (workspace->activeSubWindow() ? "exists" : "does not exist");
    qDebug() << "  Is our new window active?" << (workspace->activeSubWindow() == subWindow);
    qDebug() << "  Does our new window have focus?" << subWindow->hasFocus();
/*
 * When a subwindow is closed, make sure to remove it from both windowActions and orderedSubWindows.
 * You can do this by connecting to the subWindow's destroyed signal:
 * We put this connect function here right before updateWindowMenu so that we don't have to
 * call it twice: once in connect and once outside of connect.
*/
    connect(subWindow, &QObject::destroyed, this, [this, subWindow]() {
        QAction* action = windowActions.take(subWindow);
        if (action) {
            windowMenu->removeAction(action);
            // delete action;
        }
        orderedSubWindows.removeOne(subWindow);
        //updateWindowMenu();
    });
    updateWindowMenu();  // Update menu when a new subwindow is created
}

openFile.cpp

void MdiWindow::openFile()
{
    QString filename = QFileDialog::getOpenFileName(this, tr("Open file"),
                                                    "",
                                                    tr("Text Files (*.txt);;All Files (*)")
                                                    );
    if(filename.isEmpty())
        return;

    QFile file(filename);
    if(!file.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        QMessageBox::warning(this, tr("Error"),
                             tr("Cannot open file: ") + file.errorString(),
                             QMessageBox::Ok
        );
        return;
    }

    QTextStream in(&file);
    QString content = in.readAll();
    file.close();

    if(content.isEmpty())
    {
        QMessageBox::information(this, tr("Empty File"), tr("The selected file is empty."));
        return;
    }

    // if (!workspace->activeSubWindow() && !workspace->subWindowList().isEmpty()) {
    //     workspace->setActiveSubWindow(workspace->subWindowList().first());
    // }

    DocumentWindow *docToUse = nullptr;

    // First, check if the active document is blank to open a text file.
    QMdiSubWindow *activeSubWindow = workspace->activeSubWindow();

    qDebug() << "Number of subwindows:" << workspace->subWindowList().size();
    qDebug() << "Active subwindow before if(activeSubWindow):" << (workspace->activeSubWindow() ? "exists" : "does not exist");
   
    if(activeSubWindow)
    {
        qDebug() << "Active subwindow exists inside if(activeSubWindow) ";
        DocumentWindow *activeDoc = qobject_cast<DocumentWindow*>(activeSubWindow->widget());
        if(activeDoc && activeDoc->toPlainText().isEmpty())
        {
            docToUse = activeDoc;
            showTextFile(docToUse, content, filename);
        }
        else
        {
            QList<QMdiSubWindow *> subWindows = workspace->subWindowList();
            for(QMdiSubWindow *subWindow : subWindows)
            {
                DocumentWindow *doc = qobject_cast<DocumentWindow*>(subWindow->widget());
                if(doc && doc->toPlainText().isEmpty())
                {
                    workspace->setActiveSubWindow(subWindow);
                    docToUse = doc;
                    showTextFile(docToUse, content, filename);
                    break;
                }
            }
        }

    }
    else
    {
        // Create a new subwindow and put the text file on it.
        docToUse = new DocumentWindow();
        QMdiSubWindow *subWindow = workspace->addSubWindow(docToUse);
        showTextFile(docToUse, content, filename);
        // Unlike the exisiting subwindows above, this is a new one so we must do the following chores for it.
        connect(docToUse, &DocumentWindow::copyAvailable, this, &MdiWindow::updateEditActions);
        subWindow->show();
        workspace->setActiveSubWindow(subWindow);
        enableActions();
        updateWindowMenu();
    }
}