QVariant cause Access Violation after resume it value to pointer to class method

namespace Ui {
class Form;
}
class Form : public QWidget {
    Q_OBJECT
private:
    void (*CallbackFunc)(QVariantMap*);public:    explicit Form(QWidget *parent = nullptr);    ~Form();
signals:
    void Process(QVariantMap msg);
private slots:
    void on_pushButton_clicked();
private:
    Ui::Form *ui;
};

typedef void (Form::*FormFuncType)(void);
Q_DECLARE_METATYPE(FormFuncType)

class AppThread : public QThread {
    Q_OBJECT

private:
    int argc;
    char ** argv;
    QApplication *app;    
public:
    Form *window;
    explicit AppThread(QObject *parent = nullptr);
    ~AppThread();
private slots:
    void onReceive(QVariantMap msg);
};


void AppThread::onReceive(QVariantMap msg)
{
// Here is ERROR!!!
    FormFuncType func = msg.value("window").value<FormFuncType>();
    if (func) (window->*func)();

// But if I do below - It Works:
    FormFuncType func = &Form::activateWindow;
    if (func) (window->*func)();
}



// i call this function before any connections:
    qRegisterMetaType<FormFuncType>("FormFuncType");


    QVariantMap msg;
 // I try some variations code:
 // msg.insert("window", &Form::activateWindow);
 // msg.insert("window",   QVariant::fromValue((FormFuncType)&Form::activateWindow));
   msg.insert("window", (FormFuncType)&Form::activateWindow);
 // signal Receive(QVariantMap msg) connected to slot onReceive(QVariantMap msg):
   emit Receive(msg)