SUMMARY
I have the full Kontact suite installed. I ran Kontact once, removed akonadi-backend-mysql and added akonadi-backend-sqlite, removed all configuration files, followed instructions from Arch Linux wiki to switch to SQLite backend (https://wiki.archlinux.org/index.php/KDE#SQLite), started Kontact, tried connecting to a Google Account unsuccessfully, went to Settings > Configure KMail > Accounts > Receiving > selected my Google account and pressed modify.

This causes a segmentation fault to akonadi_imap_resource (according to Dr. Konqi) that does not crash Kontact nor KMail, it just does not allow me to open the window for modifying the imap account.

I can modify Local Folders, however.

The Dr. Konqi popup appears reproducibly if you click on Restart and then Modify.

SOFTWARE/OS VERSIONS
Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.17.80
KDE Frameworks Version: 5.64.0
Qt Version: 5.13.1
Kernel Version: 5.0.0-32-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-7200U CPU @ 2.50GHz
Memory: 7,7 GiB

CRASH INFORMATION

Application: Google Mail (herzenschein) (akonadi_imap_resource), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fbf67cdfbc0 (LWP 13472))]

Thread 6 (Thread 0x7fbf2ca02700 (LWP 13478)):
#0  0x00007fbf61e1abf9 in __GI___poll (fds=0x7fbf18003ce0, nfds=1, timeout=9354) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fbf5bce55c9 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fbf5bce56dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbf629859db in QEventDispatcherGlib::processEvents (this=0x7fbf18000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#4  0x00007fbf62925eaa in QEventLoop::exec (this=this@entry=0x7fbf2ca019e0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:225
#5  0x00007fbf627413ca in QThread::exec (this=<optimized out>) at thread/qthread.cpp:531
#6  0x00007fbf62742b72 in QThreadPrivate::start (arg=0x56464d6ba860) at thread/qthread_unix.cpp:360
#7  0x00007fbf5e3c96db in start_thread (arg=0x7fbf2ca02700) at pthread_create.c:463
#8  0x00007fbf61e2788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 5 (Thread 0x7fbf2d203700 (LWP 13476)):
#0  0x00007fbf61e160b4 in __GI___libc_read (fd=9, buf=0x7fbf2d2027d0, nbytes=16) at ../sysdeps/unix/sysv/linux/read.c:27
#1  0x00007fbf5bd2a2d0 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fbf5bce50b7 in g_main_context_check () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbf5bce5570 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fbf5bce56dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fbf629859db in QEventDispatcherGlib::processEvents (this=0x7fbf24000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#6  0x00007fbf62925eaa in QEventLoop::exec (this=this@entry=0x7fbf2d2029e0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:225
#7  0x00007fbf627413ca in QThread::exec (this=<optimized out>) at thread/qthread.cpp:531
#8  0x00007fbf62742b72 in QThreadPrivate::start (arg=0x56464d659cb0) at thread/qthread_unix.cpp:360
#9  0x00007fbf5e3c96db in start_thread (arg=0x7fbf2d203700) at pthread_create.c:463
#10 0x00007fbf61e2788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7fbf2da04700 (LWP 13475)):
#0  0x00007fbf5bd2b664 in g_mutex_unlock () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fbf5bce4b18 in g_main_context_prepare () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fbf5bce54fb in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbf5bce56dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fbf629859db in QEventDispatcherGlib::processEvents (this=0x7fbf20000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:425
#5  0x00007fbf62925eaa in QEventLoop::exec (this=this@entry=0x7fbf2da039b0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:225
#6  0x00007fbf627413ca in QThread::exec (this=this@entry=0x7fbf646b9d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread.cpp:531
#7  0x00007fbf644420e5 in QDBusConnectionManager::run (this=0x7fbf646b9d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at qdbusconnection.cpp:178
#8  0x00007fbf62742b72 in QThreadPrivate::start (arg=0x7fbf646b9d80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at thread/qthread_unix.cpp:360
#9  0x00007fbf5e3c96db in start_thread (arg=0x7fbf2da04700) at pthread_create.c:463
#10 0x00007fbf61e2788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7fbf2fc51700 (LWP 13474)):
#0  0x00007fbf5e3cf9f3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x56464d344928) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
#1  __pthread_cond_wait_common (abstime=0x0, mutex=0x56464d3448d8, cond=0x56464d344900) at pthread_cond_wait.c:502
#2  __pthread_cond_wait (cond=0x56464d344900, mutex=0x56464d3448d8) at pthread_cond_wait.c:655
#3  0x00007fbf30f242cb in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#4  0x00007fbf30f23ff7 in ?? () from /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
#5  0x00007fbf5e3c96db in start_thread (arg=0x7fbf2fc51700) at pthread_create.c:463
#6  0x00007fbf61e2788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7fbf39b5a700 (LWP 13473)):
#0  0x00007fbf61e1abf9 in __GI___poll (fds=0x7fbf39b598e8, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007fbf5da1b747 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007fbf5da1d36a in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007fbf3baa5f00 in QXcbEventQueue::run (this=0x56464d2ebe10) at qxcbeventqueue.cpp:228
#4  0x00007fbf62742b72 in QThreadPrivate::start (arg=0x56464d2ebe10) at thread/qthread_unix.cpp:360
#5  0x00007fbf5e3c96db in start_thread (arg=0x7fbf39b5a700) at pthread_create.c:463
#6  0x00007fbf61e2788f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7fbf67cdfbc0 (LWP 13472)):
[KCrash Handler]
#6  QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::operator-> (this=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:118
#7  qGetPtrHelper<QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> > > (ptr=...) at ../../include/QtCore/../../src/corelib/global/qglobal.h:1055
#8  QWindow::d_func (this=<optimized out>) at ../../include/QtGui/../../src/gui/kernel/qwindow.h:98
#9  QWindow::setTransientParent (this=this@entry=0x0, parent=parent@entry=0x56464d8b5770) at kernel/qwindow.cpp:1355
#10 0x00007fbf64202a9a in KWindowSystem::setMainWindow (subWindow=0x0, mainWindowId=<optimized out>) at ./src/kwindowsystem.cpp:482
#11 0x000056464cde73ba in ImapResource::createConfigureDialog (this=0x7ffc0fdb0540, windowId=<optimized out>) at ./resources/imap/imapresource.cpp:75
#12 0x000056464cdfb5ed in ImapResourceBase::configure (this=0x7ffc0fdb0540, windowId=<optimized out>) at ./resources/imap/imapresourcebase.cpp:223
#13 0x00007fbf666df133 in Akonadi__ControlAdaptor::qt_static_metacall (_a=0x7ffc0fdafcc0, _id=4, _c=QMetaObject::InvokeMetaMethod, _o=0x56464d652300) at ./obj-x86_64-linux-gnu/src/agentbase/controladaptor.moc:175
#14 Akonadi__ControlAdaptor::qt_metacall (this=0x56464d652300, _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0x7ffc0fdafcc0) at ./obj-x86_64-linux-gnu/src/agentbase/controladaptor.moc:176
#15 0x00007fbf6444d138 in QDBusConnectionPrivate::deliverCall (this=this@entry=0x7fbf20003f10, object=object@entry=0x56464d652300, msg=..., metaTypes=..., slotIdx=<optimized out>) at qdbusintegrator.cpp:999
#16 0x00007fbf64452080 in QDBusConnectionPrivate::activateCall (this=this@entry=0x7fbf20003f10, object=0x56464d652300, flags=flags@entry=273, msg=...) at qdbusintegrator.cpp:902
#17 0x00007fbf644529fc in QDBusConnectionPrivate::activateCall (msg=..., flags=273, object=<optimized out>, this=0x7fbf20003f10) at qdbusintegrator.cpp:851
#18 QDBusConnectionPrivate::activateObject (this=0x7fbf20003f10, node=..., msg=..., pathStartPos=<optimized out>) at qdbusintegrator.cpp:1486
#19 0x00007fbf644551de in QDBusActivateObjectEvent::placeMetaCall (this=0x7fbf18009890) at qdbusintegrator.cpp:1606
#20 0x00007fbf62959272 in QObject::event (this=0x7ffc0fdb0540, e=<optimized out>) at kernel/qobject.cpp:1260
#21 0x00007fbf63ad6eac in QApplicationPrivate::notify_helper (this=this@entry=0x56464d2e8fb0, receiver=receiver@entry=0x7ffc0fdb0540, e=e@entry=0x7fbf18009890) at kernel/qapplication.cpp:3703
#22 0x00007fbf63ade4b0 in QApplication::notify (this=0x7ffc0fdb0530, receiver=0x7ffc0fdb0540, e=0x7fbf18009890) at kernel/qapplication.cpp:3449
#23 0x00007fbf62927d48 in QCoreApplication::notifyInternal2 (receiver=0x7ffc0fdb0540, event=0x7fbf18009890) at kernel/qcoreapplication.cpp:1095
#24 0x00007fbf62927f1e in QCoreApplication::sendEvent (receiver=<optimized out>, event=event@entry=0x7fbf18009890) at kernel/qcoreapplication.cpp:1490
#25 0x00007fbf6292a667 in QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x56464d2c1930) at kernel/qcoreapplication.cpp:1840
#26 0x00007fbf6292abf8 in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1694
#27 0x00007fbf629863a3 in postEventSourceDispatch (s=0x56464d339590) at kernel/qeventdispatcher_glib.cpp:277
#28 0x00007fbf5bce5417 in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#29 0x00007fbf5bce5650 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#30 0x00007fbf5bce56dc in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#31 0x00007fbf629859bf in QEventDispatcherGlib::processEvents (this=0x56464d342b40, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#32 0x00007fbf62925eaa in QEventLoop::exec (this=this@entry=0x7ffc0fdb0480, flags=..., flags@entry=...) at kernel/qeventloop.cpp:225
#33 0x00007fbf6292f220 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1403
#34 0x00007fbf6329ae4c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1788
#35 0x00007fbf63ad6e05 in QApplication::exec () at kernel/qapplication.cpp:2859
#36 0x00007fbf666c588d in Akonadi::ResourceBase::init (r=...) at ./src/agentbase/resourcebase.cpp:611
#37 0x000056464cde6ecf in Akonadi::ResourceBase::init<ImapResource> (argc=<optimized out>, argv=<optimized out>) at /usr/include/KF5/AkonadiAgentBase/resourcebase.h:199
#38 0x00007fbf61d27b97 in __libc_start_main (main=0x56464cde6d20 <main(int, char**)>, argc=3, argv=0x7ffc0fdb06b8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffc0fdb06a8) at ../csu/libc-start.c:310
#39 0x000056464cde6d5a in _start ()