Crash when switching to design mode

1  QWindow::parent                                     qwindow.cpp                683   0x7fb73efadbb0 
2  QPlatformWindow::parent                             qplatformwindow.cpp        61    0x7fb73ef99ce3 
3  QXcbWindow::hide                                    qxcbwindow.cpp             721   0x7fb73a4ca63a 
4  QWindowPrivate::setVisible                          qwindow.cpp                393   0x7fb73efb2890 
5  QWidgetWindow::setNativeWindowVisibility            qwidgetwindow.cpp          176   0x7fb73f92d9cd 
6  QWidgetPrivate::hide_sys                            qwidget.cpp                8183  0x7fb73f911643 
7  QWidgetPrivate::hide_helper                         qwidget.cpp                8111  0x7fb73f917df0 
8  QWidgetPrivate::setVisible                          qwidget.cpp                8307  0x7fb73f91c278 
9  QWidget::setParent                                  qwidget.cpp                10603 0x7fb73f91db18 
10 QWidget::setParent                                  qwidget.cpp                10539 0x7fb73f91e278 
11 QLayout::addChildWidget                             qlayout.cpp                864   0x7fb73f8f9fa3 
12 QBoxLayout::insertWidget                            qboxlayout.cpp             943   0x7fb73f8d986b 
13 QBoxLayout::addWidget                               qboxlayout.cpp             1010  0x7fb73f8d98f2 
15 ADS::FloatingWidgetTitleBar::FloatingWidgetTitleBar floatingwidgettitlebar.cpp 93    0x7fb7231f7806 
16 ADS::FloatingDockContainer::FloatingDockContainer   floatingdockcontainer.cpp  524   0x7fb7231eab09 
17 ADS::DockManagerPrivate::restoreContainer           dockmanager.cpp            139   0x7fb7231d4429 
18 ADS::DockManagerPrivate::restoreStateFromXml        dockmanager.cpp            191   0x7fb7231d4e19 
19 ADS::DockManagerPrivate::restoreState               dockmanager.cpp            283   0x7fb7231d54c9 
20 ADS::DockManager::restoreState                      dockmanager.cpp            533   0x7fb7231d55b3 
21 ADS::DockManager::restoreState                      dockmanager.cpp            514   0x7fb7231d55b3 
22 ADS::DockManager::openWorkspace                     expected.hpp               1241  0x7fb7231d67cb 
23 ADS::DockManager::initialize                        dockmanager.cpp            412   0x7fb7231db05c 
24 QmlDesigner::Internal::DesignModeWidget::setup      designmodewidget.cpp       396   0x7fb723460944 
25 QmlDesigner::Internal::DesignModeWidget::initialize designmodewidget.cpp       589   0x7fb72346106d 
26 QmlDesigner::QmlDesignerPlugin::showDesigner        qmldesignerplugin.cpp      456   0x7fb72347fd6e 
27 QtPrivate::QSlotObjectBase::call                    qobjectdefs_impl.h         363   0x7fb73e676772 
28 doActivate<false>                                   qobject.cpp                3979  0x7fb73e676772 
29 QMetaObject::activate                               qobject.cpp                4039  0x7fb73e66f130 
31 QtPrivate::QSlotObjectBase::call                    qobjectdefs_impl.h         363   0x7fb73e676772 
32 doActivate<false>                                   qobject.cpp                3979  0x7fb73e676772 
33 QMetaObject::activate                               qobject.cpp                4039  0x7fb73e66f130 
35 QtPrivate::QSlotObjectBase::call                    qobjectdefs_impl.h         363   0x7fb73e676772 
36 doActivate<false>                                   qobject.cpp                3979  0x7fb73e676772 
37 QMetaObject::activate                               qobject.cpp                4039  0x7fb73e66f130 
39 QObject::event                                      qobject.cpp                1378  0x7fb73e66829c 
40 QApplicationPrivate::notify_helper                  qapplication.cpp           3315  0x7fb73f8c6f62 
41 QCoreApplication::notifyInternal2                   qcoreapplication.cpp       1035  0x7fb73e617fda 
42 QCoreApplicationPrivate::sendPostedEvents           qcoreapplication.cpp       1813  0x7fb73e61ed3d 
43 postEventSourceDispatch                             qeventdispatcher_glib.cpp  243   0x7fb73e8bef83 
47 QEventDispatcherGlib::processEvents                 qeventdispatcher_glib.cpp  393   0x7fb73e8be90a 
48 QEventLoop::exec                                    qflags.h                   34    0x7fb73e623c9b 
49 QCoreApplication::exec                              qflags.h                   74    0x7fb73e62007e 
50 QGuiApplication::exec                               qguiapplication.cpp        1859  0x7fb73ef551cc 
51 QApplication::exec                                  qapplication.cpp           2595  0x7fb73f8c6ed5 
52 main                                                main.cpp                   815   0x40d3eb