I  am unable to reproduce but I figured it could be useful nevertheless.

This is with fresh master.

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
Core was generated by `/home/apol/devel/kde5/bin/konsole'.
Program terminated with signal SIGABRT, Aborted.
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
44            return INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
[Current thread is 1 (Thread 0x7ffb82199a80 (LWP 147047))]
(gdb) where
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x00007ffb862a1543 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007ffb86251998 in __GI_raise (sig=6) at ../sysdeps/posix/raise.c:26
#3  0x00007ffb88a905a9 in KCrash::defaultCrashHandler (sig=6) at /home/apol/devel/frameworks/kcrash/src/kcrash.cpp:618
#4  <signal handler called>
#5  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#6  0x00007ffb862a1543 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#7  0x00007ffb86251998 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#8  0x00007ffb8623b53d in __GI_abort () at abort.c:79
#9  0x00007ffb86499833 in __gnu_cxx::__verbose_terminate_handler () at /usr/src/debug/gcc/libstdc++-v3/libsupc++/vterminate.cc:95
#10 0x00007ffb864a5cfc in __cxxabiv1::__terminate (handler=<optimized out>) at /usr/src/debug/gcc/libstdc++-v3/libsupc++/eh_terminate.cc:48
#11 0x00007ffb864a5d69 in std::terminate () at /usr/src/debug/gcc/libstdc++-v3/libsupc++/eh_terminate.cc:58
#12 0x00007ffb864a5fcd in __cxxabiv1::__cxa_throw (obj=<optimized out>, tinfo=0x7ffb866291c8 <typeinfo for std::out_of_range>, dest=0x7ffb864bd710 <std::out_of_range::~out_of_range()>) at /usr/src/debug/gcc/libstdc++-v3/libsupc++/eh_throw.cc:98
#13 0x00007ffb8649c55b in std::__throw_out_of_range_fmt (__fmt=<optimized out>) at /usr/src/debug/gcc/libstdc++-v3/src/c++11/functexcept.cc:101
#14 0x00007ffb89d3bd6b in std::vector<QVector<Konsole::Character>, std::allocator<QVector<Konsole::Character> > >::_M_range_check (this=0x565210de65c0, __n=21) at /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../include/c++/12.2.0/bits/stl_vector.h:1153
#15 0x00007ffb89d34e71 in std::vector<QVector<Konsole::Character>, std::allocator<QVector<Konsole::Character> > >::at (this=0x565210de65c0, __n=21) at /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../include/c++/12.2.0/bits/stl_vector.h:1175
#16 0x00007ffb89d30eae in Konsole::Screen::setSelectionEnd (this=0x565210de65b0, x=74, y=16, trimTrailingWhitespace=false) at /home/apol/devel/frameworks/konsole/src/Screen.cpp:1662
#17 0x00007ffb89d44843 in Konsole::ScreenWindow::setSelectionEnd (this=0x565211078670, column=74, line=16, trimTrailingWhitespace=false) at /home/apol/devel/frameworks/konsole/src/ScreenWindow.cpp:145
#18 0x00007ffb89ddbdcd in Konsole::TerminalDisplay::extendSelection (this=0x56521101c060, position=...) at /home/apol/devel/frameworks/konsole/src/terminalDisplay/TerminalDisplay.cpp:1446
#19 0x00007ffb89ddc4eb in Konsole::TerminalDisplay::mouseMoveEvent (this=0x56521101c060, ev=0x7ffdf6b7db80) at /home/apol/devel/frameworks/konsole/src/terminalDisplay/TerminalDisplay.cpp:1284
#20 0x00007ffb879a9d28 in QWidget::event (this=0x56521101c060, event=0x7ffdf6b7db80) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qwidget.cpp:9033
#21 0x00007ffb89de27fa in Konsole::TerminalDisplay::event (this=0x56521101c060, event=0x7ffdf6b7db80) at /home/apol/devel/frameworks/konsole/src/terminalDisplay/TerminalDisplay.cpp:2665
#22 0x00007ffb87967ffe in QApplicationPrivate::notify_helper (this=this@entry=0x565210a56e60, receiver=receiver@entry=0x56521101c060, e=e@entry=0x7ffdf6b7db80) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qapplication.cpp:3637
#23 0x00007ffb87970592 in QApplication::notify (this=<optimized out>, receiver=0x56521101c060, e=<optimized out>) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qapplication.cpp:3081
#24 0x00007ffb86ab5988 in QCoreApplication::notifyInternal2 (receiver=0x56521101c060, event=0x7ffdf6b7db80) at /home/apol/devel/frameworks/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1064
#25 0x00007ffb8796e69e in QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0x56521101c060, event=event@entry=0x7ffdf6b7db80, alienWidget=<optimized out>, nativeWidget=0x565210b107a0, buttonDown=buttonDown@entry=0x7ffb87eac9f0 <qt_button_down>, lastMouseReceiver=..., spontaneous=true, onlyDispatchEnterLeave=false)
    at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qapplication.cpp:2619
#26 0x00007ffb879c2b58 in QWidgetWindow::handleMouseEvent (this=0x565210b40220, event=0x7ffdf6b7de30) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qwidgetwindow.cpp:683
#27 0x00007ffb879c5ee0 in QWidgetWindow::event (this=0x565210b40220, event=0x7ffdf6b7de30) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qwidgetwindow.cpp:300
#28 0x00007ffb87967ffe in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x565210b40220, e=0x7ffdf6b7de30) at /home/apol/devel/frameworks/qt5/qtbase/src/widgets/kernel/qapplication.cpp:3637
#29 0x00007ffb86ab5988 in QCoreApplication::notifyInternal2 (receiver=0x565210b40220, event=0x7ffdf6b7de30) at /home/apol/devel/frameworks/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1064
#30 0x00007ffb87143bb5 in QGuiApplicationPrivate::processMouseEvent (e=0x7ffb7c0062c0) at /home/apol/devel/frameworks/qt5/qtbase/src/gui/kernel/qguiapplication.cpp:2282
#31 0x00007ffb87116e7c in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at /home/apol/devel/frameworks/qt5/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:1169
#32 0x00007ffb83763a20 in userEventSourceDispatch (source=<optimized out>) at /home/apol/devel/frameworks/qt5/qtbase/src/platformsupport/eventdispatchers/qeventdispatcher_glib.cpp:74
#33 0x00007ffb82fdfb2b in g_main_dispatch (context=0x565210a77ac0) at ../glib/glib/gmain.c:3417
#34 g_main_context_dispatch (context=0x565210a77ac0) at ../glib/glib/gmain.c:4135
#35 0x00007ffb83035e79 in g_main_context_iterate.constprop.0 (context=context@entry=0x565210a77ac0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/glib/gmain.c:4211
#36 0x00007ffb82fdd252 in g_main_context_iteration (context=0x565210a77ac0, may_block=1) at ../glib/glib/gmain.c:4276
#37 0x00007ffb86b0d766 in QEventDispatcherGlib::processEvents (this=0x565210a246b0, flags=...) at /home/apol/devel/frameworks/qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:423
#38 0x00007ffb86ab43fb in QEventLoop::exec (this=this@entry=0x7ffdf6b7e1d0, flags=..., flags@entry=...) at ../../include/QtCore/../../../../../devel/frameworks/qt5/qtbase/src/corelib/global/qflags.h:69
#39 0x00007ffb86abc566 in QCoreApplication::exec () at ../../include/QtCore/../../../../../devel/frameworks/qt5/qtbase/src/corelib/global/qflags.h:121
#40 0x000056520ebb2264 in main (argc=1, argv=0x7ffdf6b7e708) at /home/apol/devel/frameworks/konsole/src/main.cpp:252