SUMMARY
After updating from Plasma 5.23.3 to 5.23.4 Elisa does not start anymore. It hangs on startup while throwing the following QML type unavailable errors. Nuking Elisa's cache, database and config files doesn't help.

LOGS
QQmlApplicationEngine failed to load component
qrc:/qml/ElisaMainWindow.qml:34:9: Type MediaPlayListView unavailable
qrc:/qml/MediaPlayListView.qml:269:29: Type PlayListEntry unavailable
qrc:/qml/PlayListEntry.qml:38:27: Type MediaTrackMetadataView unavailable
qrc:/qml/MediaTrackMetadataView.qml:71:17: Type MediaTrackMetadataForm unavailable
qrc:/qml/MediaTrackMetadataForm.qml:74:13: Type MediaTrackMetadataDelegate unavailable
qrc:/qml/MediaTrackMetadataDelegate.qml:133:13: Type TextArea unavailable
file:///usr/lib/x86_64-linux-gnu/qt5/qml/QtQuick/Controls.2/org.kde.desktop/TextArea.qml:15:1: module "org.kde.sonnet" is not installed

BACKTRACE
(gdb) bt
#0  0x00007ffff623aaff in __GI___poll (fds=0x7fffe8007430, nfds=3, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007ffff41cc36e in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007ffff41cc4a3 in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007ffff680a602 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007ffff67ae8ab in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007ffff67b6a64 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x000055555555989d in main (argc=<optimized out>, argv=<optimized out>) at ./src/main.cpp:171

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.23
KDE Plasma Version: 5.23.4
Graphics Platform: X11
Cannot give more info because Bug 446555