SUMMARY
In ~/.config/kdeglobals, when you change the values for ForegroundLink or ForegroundNormal in Colors:View or Colors:Window, causes systemsettings to crash when you try to access Display and Monitor -> Compositor

STEPS TO REPRODUCE
1. Go to ~/.config/kdeglobals
2. Change the values for ForegroundLink or ForegroundNormal in Colors:View or Colors:Window
3. Access Display and Monitor -> Compositor

OBSERVED RESULT
Systemsettings crashes.

EXPECTED RESULT
Systemsettings doesn't crash and I can change the options for Compositor.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 5.3.7-arch1-1-ARCH 64-bit
KDE Plasma Version: 5.17.1
KDE Frameworks Version: 5.63.0
Qt Version: 5.13.1

ADDITIONAL INFORMATION

I am using full Sweet theme suite, so the colors were set by Sweet.

There is no problem when I create a new user on the used system.

I have attached information given by KDE Crash Handler and console output when I start systemsettings from the console.

# KDE CRASH HANDLER OUTPUT

Application: System Settings (systemsettings5), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fdeb2a6c800 (LWP 2426))]

Thread 5 (Thread 0x7fde97bff700 (LWP 2436)):
#0  0x00007fdeb551a637 in ?? () from /usr/lib/libglib-2.0.so.0
#1  0x00007fdeb551a82f in g_main_context_check () from /usr/lib/libglib-2.0.so.0
#2  0x00007fdeb551c118 in ?? () from /usr/lib/libglib-2.0.so.0
#3  0x00007fdeb551c241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#4  0x00007fdeb7cd5a1c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fdeb7c7c4ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fdeb7aae385 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#7  0x00007fdeb6db7849 in ?? () from /usr/lib/libQt5Qml.so.5
#8  0x00007fdeb7aaf5b0 in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fdeb630b4cf in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fdeb773b2d3 in clone () from /usr/lib/libc.so.6

Thread 4 (Thread 0x7fdea22fc700 (LWP 2435)):
#0  0x00007fdeb77309ef in poll () from /usr/lib/libc.so.6
#1  0x00007fdeb551c170 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007fdeb551c241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#3  0x00007fdeb7cd5a1c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#4  0x00007fdeb7c7c4ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fdeb7aae385 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#6  0x00007fdeb6db7849 in ?? () from /usr/lib/libQt5Qml.so.5
#7  0x00007fdeb7aaf5b0 in ?? () from /usr/lib/libQt5Core.so.5
#8  0x00007fdeb630b4cf in start_thread () from /usr/lib/libpthread.so.0
#9  0x00007fdeb773b2d3 in clone () from /usr/lib/libc.so.6

Thread 3 (Thread 0x7fdea8898700 (LWP 2433)):
#0  0x00007fdeb772c42c in read () from /usr/lib/libc.so.6
#1  0x00007fdeb54cc9f0 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007fdeb551aa31 in g_main_context_check () from /usr/lib/libglib-2.0.so.0
#3  0x00007fdeb551c118 in ?? () from /usr/lib/libglib-2.0.so.0
#4  0x00007fdeb551c241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#5  0x00007fdeb7cd5a1c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fdeb7c7c4ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#7  0x00007fdeb7aae385 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#8  0x00007fdeb6db7849 in ?? () from /usr/lib/libQt5Qml.so.5
#9  0x00007fdeb7aaf5b0 in ?? () from /usr/lib/libQt5Core.so.5
#10 0x00007fdeb630b4cf in start_thread () from /usr/lib/libpthread.so.0
#11 0x00007fdeb773b2d3 in clone () from /usr/lib/libc.so.6

Thread 2 (Thread 0x7fdeabfff700 (LWP 2429)):
#0  0x00007fdeb77309ef in poll () from /usr/lib/libc.so.6
#1  0x00007fdeb551c170 in ?? () from /usr/lib/libglib-2.0.so.0
#2  0x00007fdeb551c241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#3  0x00007fdeb7cd5a1c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#4  0x00007fdeb7c7c4ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fdeb7aae385 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#6  0x00007fdeb7f0fb37 in ?? () from /usr/lib/libQt5DBus.so.5
#7  0x00007fdeb7aaf5b0 in ?? () from /usr/lib/libQt5Core.so.5
#8  0x00007fdeb630b4cf in start_thread () from /usr/lib/libpthread.so.0
#9  0x00007fdeb773b2d3 in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7fdeb2a6c800 (LWP 2426)):
[KCrash Handler]
#6  0x00007fdeb71737f0 in QQuickWindowPrivate::dirtyItem(QQuickItem*) () from /usr/lib/libQt5Quick.so.5
#7  0x00007fdeb71c39e3 in QQuickText::setLinkColor(QColor const&) () from /usr/lib/libQt5Quick.so.5
#8  0x00007fdeb71cc9e0 in ?? () from /usr/lib/libQt5Quick.so.5
#9  0x00007fdeb71cce5b in QQuickText::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libQt5Quick.so.5
#10 0x00007fdeb0c7f687 in QQuickLabel::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib/libQt5QuickTemplates2.so.5
#11 0x00007fdeb6d93f37 in QV4::QQmlValueTypeWrapper::write(QObject*, int) const () from /usr/lib/libQt5Qml.so.5
#12 0x00007fdeb6d8cc16 in ?? () from /usr/lib/libQt5Qml.so.5
#13 0x00007fdeb6d8dc5d in ?? () from /usr/lib/libQt5Qml.so.5
#14 0x00007fdeb6d8a3a4 in QQmlBinding::update(QFlags<QQmlPropertyData::WriteFlag>) () from /usr/lib/libQt5Qml.so.5
#15 0x00007fdeb6d6643e in QQmlNotifier::emitNotify(QQmlNotifierEndpoint*, void**) () from /usr/lib/libQt5Qml.so.5
#16 0x00007fdeb6d034ff in QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**) () from /usr/lib/libQt5Qml.so.5
#17 0x00007fdeb7ca92eb in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQt5Core.so.5
#18 0x00007fdeaadbcf7a in ?? () from /usr/lib/libKF5Kirigami2.so.5
#19 0x00007fdeb7caa44a in QObject::event(QEvent*) () from /usr/lib/libQt5Core.so.5
#20 0x00007fdeb86d34f5 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#21 0x00007fdeb86dce11 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#22 0x00007fdeb7c7d9c2 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/libQt5Core.so.5
#23 0x00007fdeb7c80739 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/libQt5Core.so.5
#24 0x00007fdeb7cd6404 in ?? () from /usr/lib/libQt5Core.so.5
#25 0x00007fdeb551a3ee in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#26 0x00007fdeb551c201 in ?? () from /usr/lib/libglib-2.0.so.0
#27 0x00007fdeb551c241 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#28 0x00007fdeb7cd5a03 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#29 0x00007fdeb7c7c4ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#30 0x00007fdeb7c84326 in QCoreApplication::exec() () from /usr/lib/libQt5Core.so.5
#31 0x000055aa18638475 in ?? ()
#32 0x00007fdeb7663153 in __libc_start_main () from /usr/lib/libc.so.6
#33 0x000055aa186384fe in _start ()
[Inferior 1 (process 2426) detached]

#KDE CRASH HANDLER OUTPUT END

# CONSOLE OUTPUT
~/Documents ⌚ 17:48:19
$ systemsettings5
Icon theme "gnome" not found.
Icon theme "ubuntu-mono-dark" not found.
Icon theme "Mint-X" not found.
Icon theme "elementary" not found.
Icon theme "gnome" not found.
Icon theme "gnome" not found.
Icon theme "ubuntu-mono-dark" not found.
Icon theme "Mint-X" not found.
Icon theme "elementary" not found.
Icon theme "gnome" not found.
file:///usr/lib/qt/qml/org/kde/kirigami.2/SearchField.qml:47:9: QML Action: LayoutDirection attached property only works with Items and Windows
QQmlEngine::setContextForObject(): Object already has a QQmlContext
kf5.kactivity.stat: [Error at ResultSetPrivate::initQuery]:  QSqlError("1", "Unable to execute statement", "no such column: rl.initiatingAgent")
kf5.kactivity.stat: [Error at ResultSetPrivate::initQuery]:  QSqlError("1", "Unable to execute statement", "no such column: rl.initiatingAgent")
Icon theme "gnome" not found.
Icon theme "ubuntu-mono-dark" not found.
Icon theme "Mint-X" not found.
Icon theme "elementary" not found.
Icon theme "gnome" not found.
org.kde.kcoreaddons: Error loading plugin "kcm_kscreen" "The shared library was not found." 
Plugin search paths are ("/usr/lib/qt/plugins", "/usr/bin") 
The environment variable QT_PLUGIN_PATH might be not correctly set
QQmlEngine::setContextForObject(): Object already has a QQmlContext
file:///usr/lib/qt/qml/org/kde/kirigami.2/templates/InlineMessage.qml:136: TypeError: Value is undefined and could not be converted to an object
file:///usr/lib/qt/qml/org/kde/kirigami.2/templates/InlineMessage.qml:136: TypeError: Value is undefined and could not be converted to an object
file:///usr/lib/qt/qml/org/kde/kirigami.2/templates/InlineMessage.qml:136: TypeError: Value is undefined and could not be converted to an object
file:///usr/lib/qt/qml/org/kde/kirigami.2/templates/InlineMessage.qml:136: TypeError: Value is undefined and could not be converted to an object
file:///usr/lib/qt/qml/org/kde/kirigami.2/templates/InlineMessage.qml:136: TypeError: Value is undefined and could not be converted to an object
QSocketNotifier: Invalid socket 8 and type 'Read', disabling...
QSocketNotifier: Invalid socket 9 and type 'Read', disabling...
KCrash: crashing... crashRecursionCounter = 2
KCrash: Application Name = systemsettings5 path = /usr/bin pid = 2765
KCrash: Arguments: /usr/bin/systemsettings5 
KCrash: Attempting to start /usr/lib/drkonqi from kdeinit
sock_file=/run/user/1000/kdeinit5__0
[1]  + 2765 suspended (signal)  systemsettings5

~/Documents ⌚ 17:48:29
$ Unable to start Dr. Konqi
Re-raising signal for core dump handling.

[1]  + 2765 segmentation fault (core dumped)  systemsettings5

~/Documents ⌚ 17:49:29
$ 

# CONSOLE OUTPUT END