QtMacUnifiedToolBar: it crashes if the widget showing it has no title

#include <QApplication>
#include <QMainWindow>
#include "qtmacunifiedtoolbar.h"


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QMainWindow w;
   // w.setWindowTitle("Title");
    QtMacUnifiedToolBar toolBar;
    toolBar.addAction("First Action");
    toolBar.addAction("Second Action");
    toolBar.showInWindow(w.windowHandle());
    w.show();
    
    return a.exec();
}