Logged out and then logged in quickly and got a black screen with mouse pointer due to kwin_wayland crash.

Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.26.80
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.7
Graphics Platform: Wayland


Thread 7 (Thread 0x7f77f3cdc640 (LWP 12946)):
#0  __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x55c8288d1758) at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x55c8288d1758) at ./nptl/futex-internal.c:87
#2  __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x55c8288d1758, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139
#3  0x00007f7805693ac1 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x55c8288d1708, cond=0x55c8288d1730) at ./nptl/pthread_cond_wait.c:503
#4  ___pthread_cond_wait (cond=cond@entry=0x55c8288d1730, mutex=mutex@entry=0x55c8288d1708) at ./nptl/pthread_cond_wait.c:627
#5  0x00007f77fa0bf85b in cnd_wait (mtx=0x55c8288d1708, cond=0x55c8288d1730) at ../include/c11/threads_posix.h:155
#6  util_queue_thread_func (input=input@entry=0x55c8288d0b80) at ../src/util/u_queue.c:294
#7  0x00007f77fa0bf48b in impl_thrd_routine (p=<optimized out>) at ../include/c11/threads_posix.h:87
#8  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#9  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 6 (Thread 0x7f77f34db640 (LWP 12947)):
#0  0x00007f7805718d7f in __GI___poll (fds=0x7f77e40029e0, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f78040a6666 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f780404f3e3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f7806915af8 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f77e4000b70, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#4  0x00007f78068ba9bb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7f77f34dab40, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#5  0x00007f78066cd4e2 in QThread::exec() (this=<optimized out>) at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#6  0x00007f78066ce703 in QThreadPrivate::start(void*) (arg=0x55c8288ca3c8) at thread/qthread_unix.cpp:330
#7  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#8  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 5 (Thread 0x7f77f21ff640 (LWP 12955)):
#0  __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x7f77fb9cc550) at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x7f77fb9cc550) at ./nptl/futex-internal.c:87
#2  __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x7f77fb9cc550, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139
#3  0x00007f7805693ac1 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7f77fb9cc500, cond=0x7f77fb9cc528) at ./nptl/pthread_cond_wait.c:503
#4  ___pthread_cond_wait (cond=cond@entry=0x7f77fb9cc528, mutex=mutex@entry=0x7f77fb9cc500) at ./nptl/pthread_cond_wait.c:627
#5  0x00007f77fa0bf85b in cnd_wait (mtx=0x7f77fb9cc500, cond=0x7f77fb9cc528) at ../include/c11/threads_posix.h:155
#6  util_queue_thread_func (input=input@entry=0x55c828a38340) at ../src/util/u_queue.c:294
#7  0x00007f77fa0bf48b in impl_thrd_routine (p=<optimized out>) at ../include/c11/threads_posix.h:87
#8  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#9  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 4 (Thread 0x7f7800fff640 (LWP 12942)):
#0  0x00007f7805718d7f in __GI___poll (fds=0x7f77fc0053c0, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f78040a6666 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f780404f3e3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f7806915af8 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f77fc000b70, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#4  0x00007f78068ba9bb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7f7800ffeb10, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#5  0x00007f78066cd4e2 in QThread::exec() (this=this@entry=0x7f780890cd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#6  0x00007f7808893f1b in QDBusConnectionManager::run() (this=0x7f780890cd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at ./src/dbus/qdbusconnection.cpp:179
#7  0x00007f78066ce703 in QThreadPrivate::start(void*) (arg=0x7f780890cd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:330
#8  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#9  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 3 (Thread 0x7f77f0881640 (LWP 12965)):
#0  0x00007f7805718d7f in __GI___poll (fds=0x7f77d40029e0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f78040a6666 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f780404f3e3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f7806915af8 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f77d4000b70, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#4  0x00007f78068ba9bb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7f77f0880b20, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#5  0x00007f78066cd4e2 in QThread::exec() (this=this@entry=0x55c828bb8210) at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#6  0x00007f7807932959 in QQmlThreadPrivate::run() (this=0x55c828bb8210) at qml/ftw/qqmlthread.cpp:155
#7  0x00007f78066ce703 in QThreadPrivate::start(void*) (arg=0x55c828bb8210) at thread/qthread_unix.cpp:330
#8  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#9  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 2 (Thread 0x7f77f19fe640 (LWP 12956)):
#0  __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x7f77f2ca7550) at ./nptl/futex-internal.c:57
#1  __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x7f77f2ca7550) at ./nptl/futex-internal.c:87
#2  __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x7f77f2ca7550, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139
#3  0x00007f7805693ac1 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x7f77f2ca7500, cond=0x7f77f2ca7528) at ./nptl/pthread_cond_wait.c:503
#4  ___pthread_cond_wait (cond=cond@entry=0x7f77f2ca7528, mutex=mutex@entry=0x7f77f2ca7500) at ./nptl/pthread_cond_wait.c:627
#5  0x00007f77fa0bf85b in cnd_wait (mtx=0x7f77f2ca7500, cond=0x7f77f2ca7528) at ../include/c11/threads_posix.h:155
#6  util_queue_thread_func (input=input@entry=0x55c8289ec960) at ../src/util/u_queue.c:294
#7  0x00007f77fa0bf48b in impl_thrd_routine (p=<optimized out>) at ../include/c11/threads_posix.h:87
#8  0x00007f7805694b43 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#9  0x00007f7805726a00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Thread 1 (Thread 0x7f78018969c0 (LWP 12901)):
#0  std::__shared_ptr<KWin::OutputMode, (__gnu_cxx::_Lock_policy)2>::operator bool() const (this=0x38) at /usr/include/c++/11/bits/shared_ptr_base.h:1299
#1  KWin::Output::modeSize() const (this=0x0) at ./src/core/output.cpp:194
#2  0x00007f7808586aa3 in KWin::LibInput::Connection::processEvents() (this=0x55c8289898d0) at ./src/backends/libinput/connection.cpp:383
#3  0x00007f78068e9afe in QObject::event(QEvent*) (this=0x55c8288ca3b0, e=0x7f77e4006890) at kernel/qobject.cpp:1347
#4  0x00007f7805f6c763 in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=<optimized out>, receiver=0x55c8288ca3b0, e=0x7f77e4006890) at kernel/qapplication.cpp:3637
#5  0x00007f78068bc09a in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x55c8288ca3b0, event=0x7f77e4006890) at kernel/qcoreapplication.cpp:1064
#6  0x00007f78068bf187 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=data@entry=0x55c8287f6c40) at kernel/qcoreapplication.cpp:1821
#7  0x00007f7806912f5e in QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x55c8287fa7c0, flags=...) at kernel/qeventdispatcher_unix.cpp:468
#8  0x000055c826cf64a1 in QUnixEventDispatcherQPA::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
#9  0x00007f78068ba9bb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7fffbbb796a0, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:69
#10 0x00007f78068c2f54 in QCoreApplication::exec() () at ../../include/QtCore/../../src/corelib/global/qflags.h:121
#11 0x00007f7806d364e0 in QGuiApplication::exec() () at kernel/qguiapplication.cpp:1870
#12 0x00007f7805f6c6d9 in QApplication::exec() () at kernel/qapplication.cpp:2829
#13 0x000055c826c150c0 in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at ./src/main_wayland.cpp:628