Description of problem:

I logged into Plasma 5.17.90 on Wayland in Fedora Rawhide with KF5 5.66.0, Qt 5.13.2. Dr. Konqi immediately showed a segmentation fault in kded5 in KWayland::Client::OutputManagement::createConfiguration(QObject*) (this=0x0, parent=<optimized out>) at /usr/src/debug/kf5-kwayland-5.66.0-1.fc32.x86_64/x86_64-redhat-linux-gnu/src/client/wayland-output-management-client-protocol.h:226. this=0x0 might indicate a problem with a null pointer.

Application: kded5 (kded5), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
29	  return SYSCALL_CANCEL (poll, fds, nfds, timeout);
[Current thread is 1 (Thread 0x7f1fa8b4d800 (LWP 1350))]

Thread 5 (Thread 0x7f1f8e23f700 (LWP 1381)):
#0  0x00007f1fa7c269af in __GI___poll (fds=0x55d0cbdf2490, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f1fa6df9e1e in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x55d0cbdf2490, timeout=<optimized out>, context=0x55d0cbe13540) at ../glib/gmain.c:4309
#2  g_main_context_iterate (context=context@entry=0x55d0cbe13540, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4005
#3  0x00007f1fa6df9f53 in g_main_context_iteration (context=0x55d0cbe13540, may_block=1) at ../glib/gmain.c:4071
#4  0x00007f1f8e252abd in dconf_gdbus_worker_thread () at /usr/lib64/gio/modules/libdconfsettings.so
#5  0x00007f1fa6e23682 in g_thread_proxy (data=0x55d0cbdcfd40) at ../glib/gthread.c:805
#6  0x00007f1fa7781482 in start_thread (arg=<optimized out>) at pthread_create.c:477
#7  0x00007f1fa7c31583 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7f1f8ffff700 (LWP 1372)):
#0  __GI___libc_read (nbytes=16, buf=0x7f1f8fffecc0, fd=15) at ../sysdeps/unix/sysv/linux/read.c:26
#1  __GI___libc_read (fd=15, buf=buf@entry=0x7f1f8fffecc0, nbytes=nbytes@entry=16) at ../sysdeps/unix/sysv/linux/read.c:24
#2  0x00007f1fa6e422cf in read (__nbytes=16, __buf=0x7f1f8fffecc0, __fd=<optimized out>) at /usr/include/bits/unistd.h:44
#3  g_wakeup_acknowledge (wakeup=0x55d0cbddac60) at ../glib/gwakeup.c:210
#4  0x00007f1fa6df9967 in g_main_context_check (context=context@entry=0x55d0cbde00e0, max_priority=2147483647, fds=fds@entry=0x55d0cbde1f80, n_fds=n_fds@entry=1) at ../glib/gmain.c:3788
#5  0x00007f1fa6df9dc2 in g_main_context_iterate (context=0x55d0cbde00e0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4007
#6  0x00007f1fa6dfa1a3 in g_main_loop_run (loop=0x55d0cbde01d0) at ../glib/gmain.c:4204
#7  0x00007f1f94f75b7a in gdbus_shared_thread_func (user_data=0x55d0cbde00b0) at ../gio/gdbusprivate.c:279
#8  0x00007f1fa6e23682 in g_thread_proxy (data=0x55d0cbdcf4a0) at ../glib/gthread.c:805
#9  0x00007f1fa7781482 in start_thread (arg=<optimized out>) at pthread_create.c:477
#10 0x00007f1fa7c31583 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7f1f949bf700 (LWP 1371)):
#0  0x00007f1fa7c269af in __GI___poll (fds=0x55d0cbdcd9e0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f1fa6df9e1e in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x55d0cbdcd9e0, timeout=<optimized out>, context=0x55d0cbdcf2b0) at ../glib/gmain.c:4309
#2  g_main_context_iterate (context=context@entry=0x55d0cbdcf2b0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4005
#3  0x00007f1fa6df9f53 in g_main_context_iteration (context=0x55d0cbdcf2b0, may_block=may_block@entry=1) at ../glib/gmain.c:4071
#4  0x00007f1fa6df9fa1 in glib_worker_main (data=<optimized out>) at ../glib/gmain.c:5959
#5  0x00007f1fa6e23682 in g_thread_proxy (data=0x55d0cbdcf400) at ../glib/gthread.c:805
#6  0x00007f1fa7781482 in start_thread (arg=<optimized out>) at pthread_create.c:477
#7  0x00007f1fa7c31583 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7f1f95a87700 (LWP 1364)):
#0  0x00007f1fa7c269af in __GI___poll (fds=0x7f1f900029e0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f1fa6df9e1e in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x7f1f900029e0, timeout=<optimized out>, context=0x7f1f90000c30) at ../glib/gmain.c:4309
#2  g_main_context_iterate (context=context@entry=0x7f1f90000c30, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4005
#3  0x00007f1fa6df9f53 in g_main_context_iteration (context=0x7f1f90000c30, may_block=may_block@entry=1) at ../glib/gmain.c:4071
#4  0x00007f1fa81c58b3 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f1f90000b60, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007f1fa816f24b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7f1f95a86d70, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#6  0x00007f1fa7fbfc75 in QThread::exec() (this=this@entry=0x7f1fa8583060 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#7  0x00007f1fa84fff6a in QDBusConnectionManager::run() (this=0x7f1fa8583060 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:178
#8  0x00007f1fa7fc0dc6 in QThreadPrivate::start(void*) (arg=0x7f1fa8583060 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:360
#9  0x00007f1fa7781482 in start_thread (arg=<optimized out>) at pthread_create.c:477
#10 0x00007f1fa7c31583 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7f1fa8b4d800 (LWP 1350)):
[KCrash Handler]
#6  KWayland::Client::OutputManagement::createConfiguration(QObject*) (this=0x0, parent=<optimized out>) at /usr/src/debug/kf5-kwayland-5.66.0-1.fc32.x86_64/x86_64-redhat-linux-gnu/src/client/wayland-output-management-client-protocol.h:226
#7  0x00007f1f8d4a5833 in KScreen::WaylandConfig::applyConfig(QSharedPointer<KScreen::Config> const&) (this=0x55d0cbd217e0, newConfig=...) at /usr/src/debug/libkscreen-qt5-5.17.90-2.fc32.x86_64/backends/kwayland/waylandconfig.cpp:330
#8  0x00007f1f8d914a83 in KScreen::SetConfigOperation::start() (this=0x55d0cbede330) at /usr/src/debug/libkscreen-qt5-5.17.90-2.fc32.x86_64/src/setconfigoperation.cpp:129
#9  0x00007f1fa819b80a in QObject::event(QEvent*) (this=0x55d0cbede330, e=<optimized out>) at kernel/qobject.cpp:1260
#10 0x00007f1fa8d97ab6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=this@entry=0x55d0cbc50390, receiver=receiver@entry=0x55d0cbede330, e=e@entry=0x55d0cbec9ed0) at kernel/qapplication.cpp:3703
#11 0x00007f1fa8da1150 in QApplication::notify(QObject*, QEvent*) (this=0x7ffdfeb87f20, receiver=0x55d0cbede330, e=0x55d0cbec9ed0) at kernel/qapplication.cpp:3449
#12 0x00007f1fa8170458 in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x55d0cbede330, event=0x55d0cbec9ed0) at kernel/qcoreapplication.cpp:1095
#13 0x00007f1fa817349b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=0x0, event_type=0, data=0x55d0cbc50510) at kernel/qcoreapplication.cpp:1840
#14 0x00007f1fa81c5b07 in postEventSourceDispatch(GSource*, GSourceFunc, gpointer) (s=s@entry=0x55d0cbc88460) at kernel/qeventdispatcher_glib.cpp:277
#15 0x00007f1fa6df9b20 in g_main_dispatch (context=0x55d0cbc53b90) at ../glib/gmain.c:3272
#16 g_main_context_dispatch (context=context@entry=0x55d0cbc53b90) at ../glib/gmain.c:3937
#17 0x00007f1fa6df9eb0 in g_main_context_iterate (context=context@entry=0x55d0cbc53b90, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4010
#18 0x00007f1fa6df9f53 in g_main_context_iteration (context=0x55d0cbc53b90, may_block=may_block@entry=1) at ../glib/gmain.c:4071
#19 0x00007f1fa81c5895 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x55d0cbc7adb0, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#20 0x00007f1fa816f24b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7ffdfeb87e60, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#21 0x00007f1fa8177126 in QCoreApplication::exec() () at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#22 0x000055d0cb748bf2 in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/kf5-kded-5.66.0-1.fc32.x86_64/src/kded.cpp:804
[Inferior 1 (process 1350) detached]

Version-Release number of selected component (if applicable):
kf5-kded-5.66.0-1.fc32.x86_64
plasma-desktop-5.17.90-1.fc32.x86_64
qt5-qtbase-5.13.2-1.fc32.x86_64

How reproducible:
I've seen this kded5 segmentation fault 2/3 logins to Plasma 5.17.90. I haven't seen this crash with 5.17.5 or earlier.

Steps to Reproduce:
1. Boot Fedora Rawhide KDE Plasma spin fully updated with kwin-wayland, plasma-workspaces-wayland and their dependencies installed
2. Log in to Plasma on Wayland
3. Update to Plasma 5.17.90 from koji or the repository when available
4. Reboot/log out
5. Log in to Plasma 5.17.90 on Wayland

Actual results:
kded5 segmentation faults in KWayland::Client::OutputManagement::createConfiguration when logging into Plasma 5.17.90 on Wayland

Expected results:
No crashes would happen.

Additional info:

The following notification was shown 3/3 times I've logged into Plasma 5.17.90. I don't know if the notification was related to the kded5 crashes.

Error loading QML file: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/main.qml:108:37: Type CompactRepresentation unavailable
file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/CompactRepresentation.qml:27:1: module "org.kde.quickcharts" is not installed

I reported these crashes at https://bugs.kde.org/show_bug.cgi?id=416566