SUMMARY
I exported a screenshot from spectacle to gwenview, I added "Crop" button to gwenview toolbar, I changed "Text position" (right click on toolbar) to "Icons only, I clicked the button in toolbar to share a image using various services and gwenview crashed.

Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.15.80
KDE Frameworks Version: 5.58.0
Qt Version: 5.12.0


Thread 3 (Thread 0x7fb45afa9700 (LWP 26463)):
#0  0x00007fb4831519f3 in futex_wait_cancelable (private=<optimized out>, expected=0, 
    futex_word=0x55f0170795a8) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
#1  __pthread_cond_wait_common (abstime=0x0, mutex=0x55f017079558, cond=0x55f017079580)
    at pthread_cond_wait.c:502
#2  __pthread_cond_wait (cond=0x55f017079580, mutex=0x55f017079558) at pthread_cond_wait.c:655
#3  0x00007fb45b6e4dcb in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#4  0x00007fb45b6e4af7 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#5  0x00007fb48314b6db in start_thread (arg=0x7fb45afa9700) at pthread_create.c:463
#6  0x00007fb488ff588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fb46bfff700 (LWP 26461)):
#0  0x00007fb488fe8bf9 in __GI___poll (fds=0x7fb464011b40, nfds=1, timeout=-1)
    at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fb4816455c9 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb4816456dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb48992b15b in QEventDispatcherGlib::processEvents (this=0x7fb464000b20, flags=...)
    at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007fb4898cc64a in QEventLoop::exec (this=this@entry=0x7fb46bffecb0, flags=..., 
    flags@entry=...) at kernel/qeventloop.cpp:225
#5  0x00007fb4896f441a in QThread::exec (
    this=this@entry=0x7fb4881efd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at thread/qthread.cpp:531
#6  0x00007fb487f78015 in QDBusConnectionManager::run (
    this=0x7fb4881efd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at qdbusconnection.cpp:178
#7  0x00007fb4896f5bc2 in QThreadPrivate::start (
    arg=0x7fb4881efd80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>)
    at thread/qthread_unix.cpp:361
#8  0x00007fb48314b6db in start_thread (arg=0x7fb46bfff700) at pthread_create.c:463
#9  0x00007fb488ff588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7fb48e18b8c0 (LWP 26458)):
#0  __GI_raise (sig=<optimized out>) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007fb4844f208d in KCrash::defaultCrashHandler(int) ()
   from /usr/lib/x86_64-linux-gnu/libKF5Crash.so.5
#2  <signal handler called>
#3  QListData::begin (this=0x55f0177d4e60) at ../../include/QtCore/../../src/corelib/tools/qlist.h:116
#4  QList<QAction*>::contains_impl (t=<synthetic pointer>: <optimized out>, this=0x55f0177d4e60)
    at ../../include/QtCore/../../src/corelib/tools/qlist.h:1023
#5  QList<QAction*>::contains (t=<synthetic pointer>: <optimized out>, this=0x55f0177d4e60)
    at ../../include/QtCore/../../src/corelib/tools/qlist.h:1006
#6  QWidget::insertAction (this=0x55f017219cf0, before=before@entry=0x0, action=0x55f01725ad30)
    at kernel/qwidget.cpp:3273
#7  0x00007fb48b0e9d6a in QWidget::addAction (this=<optimized out>, action=<optimized out>)
    at kernel/qwidget.cpp:3238
#8  0x000055f014d7f7ba in Gwenview::KIPIInterface::loadPlugins (this=this@entry=0x55f01725ae20)
    at ./app/kipiinterface.cpp:285
#9  0x000055f014d804d4 in Gwenview::KIPIInterface::loadPlugins (this=<optimized out>)
    at /usr/include/x86_64-linux-gnu/qt5/QtCore/qarraydata.h:239
#10 Gwenview::KIPIInterface::pluginActions (this=0x55f01725ae20, 
    category=category@entry=KIPI::ExportPlugin) at ./app/kipiinterface.cpp:371
#11 0x000055f014d7b390 in Gwenview::KIPIExportAction::init (this=0x55f017173390)
    at ./app/kipiexportaction.cpp:92
#12 0x00007fb4898fdf3f in QtPrivate::QSlotObjectBase::call (a=0x7ffdd13abb30, r=0x55f017173390, 
    this=0x55f017173d70) at ../../include/QtCore/../../src/corelib/kernel/qobjectdefs_impl.h:394
#13 QMetaObject::activate (sender=sender@entry=0x55f017173610, signalOffset=<optimized out>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3759
#14 0x00007fb4898fe4f7 in QMetaObject::activate (sender=sender@entry=0x55f017173610, 
    m=m@entry=0x7fb48b791b80 <QMenu::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3631
#15 0x00007fb48b2219a0 in QMenu::aboutToShow (this=this@entry=0x55f017173610)
    at .moc/moc_qmenu.cpp:269
#16 0x00007fb48b2263dc in QMenu::popup (this=this@entry=0x55f017173610, p=..., 
    atAction=atAction@entry=0x0) at widgets/qmenu.cpp:2393
#17 0x00007fb48b22883b in QMenu::exec (this=0x55f017173610, p=..., action=action@entry=0x0)
    at widgets/qmenu.cpp:2670
#18 0x00007fb48b288c7e in QToolButtonPrivate::popupTimerDone (this=0x55f0177b6bf0)
    at widgets/qtoolbutton.cpp:798
#19 0x00007fb4898fde25 in QMetaObject::activate (sender=sender@entry=0x55f01757ee10, 
    signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0)
    at kernel/qobject.cpp:3778
#20 0x00007fb4898fe4f7 in QMetaObject::activate (sender=sender@entry=0x55f01757ee10, 
    m=m@entry=0x7fb48b789ba0 <QAbstractButton::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3631
#21 0x00007fb48b1998c0 in QAbstractButton::pressed (this=this@entry=0x55f01757ee10)
    at .moc/moc_qabstractbutton.cpp:299
#22 0x00007fb48b199bfd in QAbstractButtonPrivate::emitPressed (this=0x55f0177b6bf0)
    at widgets/qabstractbutton.cpp:428
#23 0x00007fb48b19a2fc in QAbstractButton::mousePressEvent (this=this@entry=0x55f01757ee10, e=e@entry=
    0x7ffdd13ac460) at widgets/qabstractbutton.cpp:983
#24 0x00007fb48b289a5a in QToolButton::mousePressEvent (this=0x55f01757ee10, e=0x7ffdd13ac460)
    at widgets/qtoolbutton.cpp:613
#25 0x00007fb48b0f31ff in QWidget::event (this=0x55f01757ee10, event=0x7ffdd13ac460)
    at kernel/qwidget.cpp:8884
#26 0x00007fb48b19c2db in QAbstractButton::event (this=this@entry=0x55f01757ee10, 
    e=e@entry=0x7ffdd13ac460) at widgets/qabstractbutton.cpp:968
#27 0x00007fb48b289ca4 in QToolButton::event (this=0x55f01757ee10, event=0x7ffdd13ac460)
    at widgets/qtoolbutton.cpp:985
#28 0x00007fb48b0b28ac in QApplicationPrivate::notify_helper (this=this@entry=0x55f016e512c0, 
    receiver=receiver@entry=0x55f01757ee10, e=e@entry=0x7ffdd13ac460) at kernel/qapplication.cpp:3752
#29 0x00007fb48b0bad18 in QApplication::notify (this=<optimized out>, receiver=0x55f01757ee10, 
    e=0x7ffdd13ac460) at kernel/qapplication.cpp:3213
#30 0x00007fb4898ce328 in QCoreApplication::notifyInternal2 (receiver=0x55f01757ee10, 
    event=0x7ffdd13ac460) at kernel/qcoreapplication.cpp:1061
#31 0x00007fb4898ce50e in QCoreApplication::sendSpontaneousEvent (
    receiver=receiver@entry=0x55f01757ee10, event=event@entry=0x7ffdd13ac460)
    at kernel/qcoreapplication.cpp:1463
#32 0x00007fb48b0b930f in QApplicationPrivate::sendMouseEvent (
    receiver=receiver@entry=0x55f01757ee10, event=event@entry=0x7ffdd13ac460, 
    alienWidget=0x55f01757ee10, nativeWidget=0x55f016ef3fa0, 
    buttonDown=buttonDown@entry=0x7fb48b7b38b0 <qt_button_down>, lastMouseReceiver=..., 
    spontaneous=true, onlyDispatchEnterLeave=false) at kernel/qapplication.cpp:2699
#33 0x00007fb48b10daf0 in QWidgetWindow::handleMouseEvent (this=this@entry=0x55f01725b130, 
    event=event@entry=0x7ffdd13ac8f0) at kernel/qwidgetwindow.cpp:661
#34 0x00007fb48b11057a in QWidgetWindow::event (this=0x55f01725b130, event=0x7ffdd13ac8f0)
    at kernel/qwidgetwindow.cpp:281
#35 0x00007fb48b0b28ac in QApplicationPrivate::notify_helper (this=this@entry=0x55f016e512c0, 
    receiver=receiver@entry=0x55f01725b130, e=e@entry=0x7ffdd13ac8f0) at kernel/qapplication.cpp:3752
#36 0x00007fb48b0b9e40 in QApplication::notify (this=0x7ffdd13acd90, receiver=0x55f01725b130, 
    e=0x7ffdd13ac8f0) at kernel/qapplication.cpp:3499
#37 0x00007fb4898ce328 in QCoreApplication::notifyInternal2 (receiver=0x55f01725b130, 
    event=0x7ffdd13ac8f0) at kernel/qcoreapplication.cpp:1061
#38 0x00007fb4898ce50e in QCoreApplication::sendSpontaneousEvent (
    receiver=receiver@entry=0x55f01725b130, event=event@entry=0x7ffdd13ac8f0)
    at kernel/qcoreapplication.cpp:1463
#39 0x00007fb48a88452b in QGuiApplicationPrivate::processMouseEvent (e=0x55f01720eab0)
    at kernel/qguiapplication.cpp:2102
#40 0x00007fb48a885695 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x55f01720eab0)
    at kernel/qguiapplication.cpp:1837
#41 0x00007fb48a85e14b in QWindowSystemInterface::sendWindowSystemEvents (flags=flags@entry=...)
    at kernel/qwindowsysteminterface.cpp:1068
#42 0x00007fb47439330a in xcbSourceDispatch (source=<optimized out>) at qxcbeventdispatcher.cpp:105
#43 0x00007fb481645417 in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#44 0x00007fb481645650 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#45 0x00007fb4816456dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#46 0x00007fb48992b13f in QEventDispatcherGlib::processEvents (this=0x55f016ea6b20, flags=...)
    at kernel/qeventdispatcher_glib.cpp:422
#47 0x00007fb4898cc64a in QEventLoop::exec (this=this@entry=0x7ffdd13acc90, flags=..., 
    flags@entry=...) at kernel/qeventloop.cpp:225
#48 0x00007fb4898d5800 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1364
#49 0x000055f014d2d7d1 in main (argc=<optimized out>, argv=<optimized out>) at ./app/main.cpp:163