Assert in Renderer::contextInfo()

When closing Scene3d example from "X" renderview job runs and crashes to non existing graphicscontext.

0 qt_message_fatal qlogging.cpp 1603 0x5a9df35b
1 QMessageLogger::fatal qlogging.cpp 784 0x5a9ddba6
2 qt_assert qglobal.cpp 3045 0x5a9d2ab2
3 QScopedPointer<Qt3DRender::Render::GraphicsContext,QScopedPointerDeleter<Qt3DRender::Render::GraphicsContext>>::operator-> qscopedpointer.h 112 0x7fee29f6c5e
4 Qt3DRender::Render::Renderer::contextInfo renderer.cpp 1017 0x7fee29ea8ec
5 Qt3DRender::Render::findTechniqueForEffect renderviewjobutils.cpp 270 0x7fee2b725a6
6 Qt3DRender::Render::RenderView::passesAndParameters renderview.cpp 411 0x7fee2a11e38
7 Qt3DRender::Render::RenderView::buildDrawRenderCommands renderview.cpp 512 0x7fee2a12308
8 Qt3DRender::Render::RenderView::buildRenderCommands renderview.cpp 495 0x7fee2a12153
9 Qt3DRender::Render::RenderView::buildRenderCommands renderview.cpp 496 0x7fee2a121d9
10 Qt3DRender::Render::RenderViewJob::run renderviewjob.cpp 90 0x7fee2b7144a
11 Qt3DCore::AspectTaskRunnable::run task.cpp 76 0x7fee2ff50d5
12 QThreadPoolThread::run qthreadpool.cpp 93 0x5a9fb47b
13 QThreadPrivate::start qthread_win.cpp 369 0x5aa03b18
14 _callthreadstartex threadex.c 376 0x7fee378a105
15 _threadstartex threadex.c 359 0x7fee378a357
16 BaseThreadInitThunk kernel32 0x779559ed
17 RtlUserThreadStart ntdll 0x77a8b831