SUMMARY
KMail crashes when opening settings with latest git master KF5

STEPS TO REPRODUCE
1. Click on settings 
2. Click on configure kmail

OBSERVED RESULT
KMail crashes. 

EXPECTED RESULT
Settings open

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: master
(available in About System)
KDE Plasma Version: master
KDE Frameworks Version: master
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Application: KMail (kmail), signal: Segmentation fault
Content of s_kcrashErrorMessage: (null)
[KCrash Handler]
#5  0x00007f259ba6ccbe in KPluginFactory::d_func (this=0x0) at /home/leszek/kde/src/kcoreaddons/src/lib/plugin/kpluginfactory.h:375
#6  0x00007f259ba6b902 in KPluginFactory::setMetaData (this=0x0, metaData=...) at /home/leszek/kde/src/kcoreaddons/src/lib/plugin/kpluginfactory.cpp:46
#7  0x00007f259ba6ef2c in KPluginLoader::factory (this=0x7ffde3c3b0c0) at /home/leszek/kde/src/kcoreaddons/src/lib/plugin/kpluginloader.cpp:113
#8  0x00007f2597ecc396 in KService::createInstance<KCModule> (this=0x56445ee339e0, parentWidget=0x0, parent=0x56445ee39430, args=..., error=0x7ffde3c3b248) at /opt/plasma5/include/KF5/KService/kservice.h:541
#9  0x00007f2597ecbabe in KService::createInstance<KCModule> (this=0x56445ee339e0, parent=0x56445ee39430, args=..., error=0x7ffde3c3b248) at /opt/plasma5/include/KF5/KService/kservice.h:520
#10 0x00007f2597eca2be in KCModuleLoader::loadModule (mod=..., report=KCModuleLoader::Inline, parent=0x56445ee39430, args=...) at /home/leszek/kde/src/kcmutils/src/kcmoduleloader.cpp:108
#11 0x00007f2597ed91c4 in KCModuleProxyPrivate::loadModule (this=0x56445ee39670) at /home/leszek/kde/src/kcmutils/src/kcmoduleproxy.cpp:81
#12 0x00007f2597ed8d44 in KCModuleProxy::realModule (this=0x56445ee39430) at /home/leszek/kde/src/kcmutils/src/kcmoduleproxy.cpp:54
#13 0x00007f2597ed5f1f in KCMultiDialog::addModule (this=0x56445ed96dd0, moduleInfo=..., parentItem=0x0, args=...) at /home/leszek/kde/src/kcmutils/src/kcmultidialog.cpp:482
#14 0x00007f2597ed5ad3 in KCMultiDialog::addModule (this=0x56445ed96dd0, path=..., args=...) at /home/leszek/kde/src/kcmutils/src/kcmultidialog.cpp:446
#15 0x00007f25a50b8b65 in ConfigureDialog::ConfigureDialog (this=0x56445ed96dd0, parent=0x0, modal=false) at /home/leszek/kde/src/kmail/src/configuredialog/configuredialog.cpp:41
#16 0x00007f25a4ff1983 in KMKernel::slotShowConfigurationDialog (this=0x7ffde3c3cb90) at /home/leszek/kde/src/kmail/src/kmkernel.cpp:1241
#17 0x00007f25a4fde623 in QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, void (KMKernel::*)()>::call(void (KMKernel::*)(), KMKernel*, void**) (f=(void (KMKernel::*)(class KMKernel * const)) 0x7f25a4ff18fe <KMKernel::slotShowConfigurationDialog()>, o=0x7ffde3c3cb90, arg=0x7ffde3c3bdf0) at /home/leszek/kde/qt5/include/QtCore/qobjectdefs_impl.h:152
#18 0x00007f25a4fddfd6 in QtPrivate::FunctionPointer<void (KMKernel::*)()>::call<QtPrivate::List<>, void>(void (KMKernel::*)(), KMKernel*, void**) (f=(void (KMKernel::*)(class KMKernel * const)) 0x7f25a4ff18fe <KMKernel::slotShowConfigurationDialog()>, o=0x7ffde3c3cb90, arg=0x7ffde3c3bdf0) at /home/leszek/kde/qt5/include/QtCore/qobjectdefs_impl.h:185
#19 0x00007f25a4fdd1d6 in QtPrivate::QSlotObject<void (KMKernel::*)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (which=1, this_=0x564456621680, r=0x7ffde3c3cb90, a=0x7ffde3c3bdf0, ret=0x0) at /home/leszek/kde/qt5/include/QtCore/qobjectdefs_impl.h:418
#20 0x00007f259a63d66c in QtPrivate::QSlotObjectBase::call (a=0x7ffde3c3bdf0, r=0x7ffde3c3cb90, this=0x564456621680) at ../../include/QtCore/../../../../../src/Qt5/qtbase/src/corelib/kernel/qobjectdefs_impl.h:398
#21 doActivate<false> (sender=0x56445660bdc0, signal_index=4, argv=0x7ffde3c3bdf0) at /home/leszek/kde/src/Qt5/qtbase/src/corelib/kernel/qobject.cpp:3886
#22 0x00007f259a637982 in QMetaObject::activate (sender=sender@entry=0x56445660bdc0, m=m@entry=0x7f259b7e7180 <QAction::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7ffde3c3bdf0) at /home/leszek/kde/src/Qt5/qtbase/src/corelib/kernel/qobject.cpp:3946
#23 0x00007f259b322242 in QAction::triggered (this=this@entry=0x56445660bdc0, _t1=<optimized out>) at .moc/moc_qaction.cpp:376
#24 0x00007f259b324626 in QAction::activate (this=0x56445660bdc0, event=<optimized out>) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qaction.cpp:1161
#25 0x00007f259b48fe2c in QMenuPrivate::activateCausedStack (this=this@entry=0x564456789230, causedStack=..., action=action@entry=0x56445660bdc0, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/widgets/qmenu.cpp:1384
#26 0x00007f259b496e80 in QMenuPrivate::activateAction (this=this@entry=0x564456789230, action=action@entry=0x56445660bdc0, action_e=action_e@entry=QAction::Trigger, self=self@entry=true) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/widgets/qmenu.cpp:1461
#27 0x00007f259b497ef8 in QMenu::mouseReleaseEvent (this=<optimized out>, e=0x7ffde3c3c3b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/widgets/qmenu.cpp:2966
#28 0x00007f259b365a88 in QWidget::event (this=this@entry=0x5644567879a0, event=event@entry=0x7ffde3c3c3b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qwidget.cpp:8663
#29 0x00007f259b49a229 in QMenu::event (this=0x5644567879a0, e=0x7ffde3c3c3b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/widgets/qmenu.cpp:3088
#30 0x00007f259b32811e in QApplicationPrivate::notify_helper (this=this@entry=0x564455fd1520, receiver=receiver@entry=0x5644567879a0, e=e@entry=0x7ffde3c3c3b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qapplication.cpp:3632
#31 0x00007f259b32eb48 in QApplication::notify (this=<optimized out>, receiver=0x5644567879a0, e=0x7ffde3c3c3b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qapplication.cpp:3076
#32 0x00007f259a60aba9 in QCoreApplication::notifyInternal2 (receiver=0x5644567879a0, event=0x7ffde3c3c3b0) at ../../include/QtCore/5.15.2/QtCore/private/../../../../../../../../src/Qt5/qtbase/src/corelib/thread/qthread_p.h:325
#33 0x00007f259b32e04f in QApplicationPrivate::sendMouseEvent (receiver=0x5644567879a0, event=event@entry=0x7ffde3c3c3b0, alienWidget=0x0, nativeWidget=0x5644567879a0, buttonDown=buttonDown@entry=0x7f259b8169b0 <qt_button_down>, lastMouseReceiver=..., spontaneous=true, onlyDispatchEnterLeave=false) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qapplication.cpp:2614
#34 0x00007f259b37fe80 in QWidgetWindow::handleMouseEvent (this=0x5644567896b0, event=0x7ffde3c3c7a0) at /usr/include/c++/8/bits/atomic_base.h:390
#35 0x00007f259b382663 in QWidgetWindow::event (event=0x7ffde3c3c7a0, this=0x5644567896b0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qwidgetwindow.cpp:300
#36 QWidgetWindow::event (this=0x5644567896b0, event=0x7ffde3c3c7a0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qwidgetwindow.cpp:239
#37 0x00007f259b32811e in QApplicationPrivate::notify_helper (this=this@entry=0x564455fd1520, receiver=receiver@entry=0x5644567896b0, e=e@entry=0x7ffde3c3c7a0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qapplication.cpp:3632
#38 0x00007f259b32e9a0 in QApplication::notify (this=0x7ffde3c3ccc0, receiver=0x5644567896b0, e=0x7ffde3c3c7a0) at /home/leszek/kde/src/Qt5/qtbase/src/widgets/kernel/qapplication.cpp:3156
#39 0x00007f259a60aba9 in QCoreApplication::notifyInternal2 (receiver=0x5644567896b0, event=0x7ffde3c3c7a0) at ../../include/QtCore/5.15.2/QtCore/private/../../../../../../../../src/Qt5/qtbase/src/corelib/thread/qthread_p.h:325
#40 0x00007f259aa2a884 in QGuiApplicationPrivate::processMouseEvent (e=0x56445ed7f9e0) at /home/leszek/kde/src/Qt5/qtbase/src/gui/kernel/qguiapplication.cpp:2282
#41 0x00007f259aa2bb75 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x56445ed7f9e0) at /home/leszek/kde/src/Qt5/qtbase/src/gui/kernel/qguiapplication.cpp:2002
#42 0x00007f259aa0717b in QWindowSystemInterface::sendWindowSystemEvents (flags=flags@entry=...) at /home/leszek/kde/src/Qt5/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:1169
#43 0x00007f258f63152a in xcbSourceDispatch (source=<optimized out>) at /home/leszek/kde/src/Qt5/qtbase/src/plugins/platforms/xcb/qxcbeventdispatcher.cpp:105
#44 0x00007f2592383f2e in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#45 0x00007f25923841c8 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#46 0x00007f259238425c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#47 0x00007f259a65e354 in QEventDispatcherGlib::processEvents (this=0x5644560a0fb0, flags=...) at /home/leszek/kde/src/Qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:423
#48 0x00007f259a609853 in QEventLoop::exec (this=this@entry=0x7ffde3c3cb30, flags=..., flags@entry=...) at ../../include/QtCore/../../../../../src/Qt5/qtbase/src/corelib/global/qflags.h:141
#49 0x00007f259a6116cc in QCoreApplication::exec () at ../../include/QtCore/../../../../../src/Qt5/qtbase/src/corelib/global/qflags.h:121
#50 0x000056445595e405 in main (argc=1, argv=0x7ffde3c3cea8) at /home/leszek/kde/src/kmail/src/main.cpp:184
[Inferior 1 (process 1150388) detached]