Comment 4 for bug 1655644

New backtrace:

Thread 1 "unity8" received signal SIGSEGV, Segmentation fault.
0x00007f31108325a5 in qtmir::SurfaceManager::onWindowRemoved(miral::WindowInfo const&) () from /usr/lib/x86_64-linux-gnu/qt5/qml/Unity/Application/libunityapplicationplugin.so
(gdb) bt
#0 0x00007f31108325a5 in qtmir::SurfaceManager::onWindowRemoved(miral::WindowInfo const&) () from /usr/lib/x86_64-linux-gnu/qt5/qml/Unity/Application/libunityapplicationplugin.so
#1 0x00007f3146399729 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#2 0x00007f314636c15a in QCoreApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3 0x00007f314636c2b8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4 0x00007f314636e17a in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5 0x00007f31463c0f63 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6 0x00007f3142f7c1a7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#7 0x00007f3142f7c400 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#8 0x00007f3142f7c4ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#9 0x00007f31463c136f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007f314636a00a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007f31463726cc in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00000000004079fa in ?? ()
#13 0x00007f31457a9830 in __libc_start_main (main=0x4077e0, argc=2, argv=0x7fff1c7fca88, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fff1c7fca78)
    at ../csu/libc-start.c:291
#14 0x0000000000407bd9 in _start ()