Oak only uses KDDockWidgets' QtWidgets frontend. Building the QtQuick frontend caused duplicate QML module registration when QtQuick.framework initialized, resulting in a SIGABRT in QQmlMetaType::qmlInsertModuleRegistration. - Set KDDockWidgets_FRONTENDS to qtwidgets in ext/CMakeLists.txt. - Remove the -qmldir flags from macOS CD deploy since QML plugins are no longer needed.