SUMMARY
System Settings crashes after clicking another menu item (or clicking close button) while Launch Feedback item selected.
The crash can be reproduced every time.

STEPS TO REPRODUCE
1. Open KDE System Settings - Applications - Launch Feedback
2. Click another menu item / close System Settings

OBSERVED RESULT
System Settings crashes

EXPECTED RESULT
Menu item successfully selected / System Settings closed

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 18.10
KDE Plasma Version: 5.13.5
KDE Frameworks Version: 5.50.0

Application: systemsettings5 (5.13.5)

Qt Version: 5.11.1
Frameworks Version: 5.50.0
Operating System: Linux 4.18.0-17-generic x86_64
Distribution: Ubuntu 18.10

-- Backtrace:
Application: Параметры системы (systemsettings5), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fae3c36a840 (LWP 3580))]

Thread 7 (Thread 0x7fae213af700 (LWP 3605)):
#0  0x00007fae427376d9 in __GI___poll (fds=0x7fae10000b20, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fae3f866e46 in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x7fae10000b20, timeout=<optimized out>, context=0x7fae10002e20) at ../../../../glib/gmain.c:4221
#2  g_main_context_iterate (context=context@entry=0x7fae10002e20, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3915
#3  0x00007fae3f866f6c in g_main_context_iteration (context=0x7fae10002e20, may_block=may_block@entry=1) at ../../../../glib/gmain.c:3981
#4  0x00007fae42c5a15b in QEventDispatcherGlib::processEvents (this=0x7fae10005b00, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007fae42c0716b in QEventLoop::exec (this=this@entry=0x7fae213aed40, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#6  0x00007fae42a560b6 in QThread::exec (this=this@entry=0x55e40fbb1120) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#7  0x00007fae41d171f5 in QQmlThreadPrivate::run (this=0x55e40fbb1120) at qml/ftw/qqmlthread.cpp:148
#8  0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x55e40fbb1120) at thread/qthread_unix.cpp:367
#9  0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#10 0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 6 (Thread 0x7fae1affe700 (LWP 3598)):
#0  __GI___libc_read (fd=38, buf=buf@entry=0x7fae1affdb20, nbytes=nbytes@entry=16) at ../sysdeps/unix/sysv/linux/read.c:26
#1  0x00007fae3f8ac180 in read (__nbytes=16, __buf=0x7fae1affdb20, __fd=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/unistd.h:44
#2  g_wakeup_acknowledge (wakeup=0x55e41018e0c0) at ../../../../glib/gwakeup.c:210
#3  0x00007fae3f86691f in g_main_context_check (context=context@entry=0x7fadf8049770, max_priority=2147483647, fds=fds@entry=0x7fadf80444a0, n_fds=n_fds@entry=1) at ../../../../glib/gmain.c:3698
#4  0x00007fae3f866df0 in g_main_context_iterate (context=context@entry=0x7fadf8049770, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3917
#5  0x00007fae3f866f6c in g_main_context_iteration (context=0x7fadf8049770, may_block=may_block@entry=1) at ../../../../glib/gmain.c:3981
#6  0x00007fae42c5a15b in QEventDispatcherGlib::processEvents (this=0x7fadf802a4e0, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#7  0x00007fae42c0716b in QEventLoop::exec (this=this@entry=0x7fae1affdd40, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#8  0x00007fae42a560b6 in QThread::exec (this=this@entry=0x55e410362100) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#9  0x00007fae41d171f5 in QQmlThreadPrivate::run (this=0x55e410362100) at qml/ftw/qqmlthread.cpp:148
#10 0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x55e410362100) at thread/qthread_unix.cpp:367
#11 0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#12 0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 5 (Thread 0x7fae28ab2700 (LWP 3586)):
#0  0x00007fae427376d9 in __GI___poll (fds=0x7fae1c003ce0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fae3f866e46 in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x7fae1c003ce0, timeout=<optimized out>, context=0x7fae1c000bf0) at ../../../../glib/gmain.c:4221
#2  g_main_context_iterate (context=context@entry=0x7fae1c000bf0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3915
#3  0x00007fae3f866f6c in g_main_context_iteration (context=0x7fae1c000bf0, may_block=may_block@entry=1) at ../../../../glib/gmain.c:3981
#4  0x00007fae42c5a15b in QEventDispatcherGlib::processEvents (this=0x7fae1c000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007fae42c0716b in QEventLoop::exec (this=this@entry=0x7fae28ab1d40, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#6  0x00007fae42a560b6 in QThread::exec (this=this@entry=0x55e40e499930) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#7  0x00007fae41d171f5 in QQmlThreadPrivate::run (this=0x55e40e499930) at qml/ftw/qqmlthread.cpp:148
#8  0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x55e40e499930) at thread/qthread_unix.cpp:367
#9  0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#10 0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7fae2a653700 (LWP 3585)):
#0  0x00007fae427376d9 in __GI___poll (fds=0x7fae24004a00, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fae3f866e46 in g_main_context_poll (priority=<optimized out>, n_fds=1, fds=0x7fae24004a00, timeout=<optimized out>, context=0x7fae24000bf0) at ../../../../glib/gmain.c:4221
#2  g_main_context_iterate (context=context@entry=0x7fae24000bf0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3915
#3  0x00007fae3f866f6c in g_main_context_iteration (context=0x7fae24000bf0, may_block=may_block@entry=1) at ../../../../glib/gmain.c:3981
#4  0x00007fae42c5a15b in QEventDispatcherGlib::processEvents (this=0x7fae24000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007fae42c0716b in QEventLoop::exec (this=this@entry=0x7fae2a652d40, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#6  0x00007fae42a560b6 in QThread::exec (this=this@entry=0x55e40df6c110) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#7  0x00007fae41d171f5 in QQmlThreadPrivate::run (this=0x55e40df6c110) at qml/ftw/qqmlthread.cpp:148
#8  0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x55e40df6c110) at thread/qthread_unix.cpp:367
#9  0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#10 0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7fae38fab700 (LWP 3583)):
#0  postEventSourceCheck (source=0x7fae2c004ba0) at kernel/qeventdispatcher_glib.cpp:269
#1  0x00007fae3f866821 in g_main_context_check (context=context@entry=0x7fae2c000bf0, max_priority=2147483647, fds=fds@entry=0x7fae2c0168e0, n_fds=n_fds@entry=1) at ../../../../glib/gmain.c:3753
#2  0x00007fae3f866df0 in g_main_context_iterate (context=context@entry=0x7fae2c000bf0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../../glib/gmain.c:3917
#3  0x00007fae3f866f6c in g_main_context_iteration (context=0x7fae2c000bf0, may_block=may_block@entry=1) at ../../../../glib/gmain.c:3981
#4  0x00007fae42c5a15b in QEventDispatcherGlib::processEvents (this=0x7fae2c000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007fae42c0716b in QEventLoop::exec (this=this@entry=0x7fae38faad30, flags=..., flags@entry=...) at ../../include/QtCore/../../src/corelib/global/qflags.h:140
#6  0x00007fae42a560b6 in QThread::exec (this=this@entry=0x7fae42f8dd60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at ../../include/QtCore/../../src/corelib/global/qflags.h:120
#7  0x00007fae42f13545 in QDBusConnectionManager::run (this=0x7fae42f8dd60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:178
#8  0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x7fae42f8dd60 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:367
#9  0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#10 0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fae3ad07700 (LWP 3582)):
#0  0x00007fae427376d9 in __GI___poll (fds=0x7fae3ad06c78, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fae40b9a917 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007fae40b9c53a in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007fae3bca4159 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#4  0x00007fae42a5fc87 in QThreadPrivate::start (arg=0x55e40db47c00) at thread/qthread_unix.cpp:367
#5  0x00007fae40bdc164 in start_thread (arg=<optimized out>) at pthread_create.c:486
#6  0x00007fae42743def in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7fae3c36a840 (LWP 3580)):
[KCrash Handler]
#6  0x00007fae4401d304 in KQuickAddons::ConfigModule::needsSave (this=0x55e4110628b0) at ./src/quickaddons/configmodule.cpp:336
#7  0x00007fae441534bb in KCModuleQml::<lambda()>::operator() (__closure=<optimized out>) at ./src/kcmoduleqml.cpp:72
#8  QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, KCModuleQml::KCModuleQml(KQuickAddons::ConfigModule*, QWidget*, const QVariantList&)::<lambda()> >::call (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:128
#9  QtPrivate::Functor<KCModuleQml::KCModuleQml(KQuickAddons::ConfigModule*, QWidget*, const QVariantList&)::<lambda()>, 0>::call<QtPrivate::List<>, void> (arg=<optimized out>, f=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:238
#10 QtPrivate::QFunctorSlotObject<KCModuleQml::KCModuleQml(KQuickAddons::ConfigModule*, QWidget*, const QVariantList&)::<lambda()>, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=<optimized out>, this_=<optimized out>, r=<optimized out>, a=<optimized out>, ret=<optimized out>) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:421
#11 0x00007fae42c31830 in QtPrivate::QSlotObjectBase::call (a=0x7ffd5c759d00, r=0x55e40fff5e10, this=0x55e40e125050) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:376
#12 QMetaObject::activate (sender=0x55e40fff5e10, signalOffset=<optimized out>, local_signal_index=<optimized out>, argv=<optimized out>) at kernel/qobject.cpp:3754
#13 0x00007fae28d7cd43 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/kcms/kcm_launchfeedback.so
#14 0x00007fae28d7f3e3 in ?? () from /usr/lib/x86_64-linux-gnu/qt5/plugins/kcms/kcm_launchfeedback.so
#15 0x00007fae41c33084 in QV4::QObjectWrapper::setProperty (engine=0x7fae3400faa0, object=<optimized out>, property=0x55e411031da8, value=...) at ../../include/QtQml/5.11.1/QtQml/private/../../../../../src/qml/qml/qqmlpropertycache_p.h:214
#16 0x00007fae41c33dde in QV4::QObjectWrapper::setQmlProperty (engine=0x7fae3400faa0, qmlContext=<optimized out>, object=0x55e40fff5e10, name=<optimized out>, revisionMode=QV4::QObjectWrapper::IgnoreRevision, value=...) at jsruntime/qv4qobjectwrapper.cpp:429
#17 0x00007fae41c33ed4 in QV4::QObjectWrapper::put (m=0x7fae1652c398, name=0x7fae1652c390, value=...) at /usr/include/c++/8/bits/atomic_base.h:390
#18 0x00007fae41c46eac in QV4::Object::put (v=..., name=<optimized out>, this=<optimized out>) at ../../include/QtQml/5.11.1/QtQml/private/../../../../../src/qml/memory/qv4heap_p.h:101
#19 QV4::Runtime::method_storeProperty (engine=engine@entry=0x7fae3400faa0, object=..., nameIndex=<optimized out>, value=...) at jsruntime/qv4runtime.cpp:549
#20 0x00007fae41c52789 in storePropertyHelper (f=0x55e410fce0b0, base=..., name=<optimized out>, value=...) at jit/qv4jit.cpp:368
#21 0x00007fae1b5d3b7d in ?? ()
#22 0x00007fae1652c320 in ?? ()
#23 0x00007fae1652c328 in ?? ()
#24 0x00007fae3400faa0 in ?? ()
#25 0x0000000000000000 in ?? ()
[Inferior 1 (process 3580) detached]