Do not ask for decoration settings without guarding

Otherwise we crash when no decoration is set (e.g. Plasma Mobile)


(cherry picked from commit ff618e9f)

src/appmenu.cpp

@@ -76,7 +76,7 @@ void ApplicationMenu::slotShowRequest(const QString &serviceName, const QDBusObj
 {
     // Ignore show request when user has not configured the application menu title bar button
     auto decorationSettings = Decoration::DecorationBridge::self()->settings();
-    if (!decorationSettings->decorationButtonsLeft().contains(KDecoration2::DecorationButtonType::ApplicationMenu)
+    if (decorationSettings && !decorationSettings->decorationButtonsLeft().contains(KDecoration2::DecorationButtonType::ApplicationMenu)
             && !decorationSettings->decorationButtonsRight().contains(KDecoration2::DecorationButtonType::ApplicationMenu)) {
         return;
     }

src/effects.cpp

@@ -1513,9 +1513,11 @@ EffectFrame* EffectsHandlerImpl::effectFrame(EffectFrameStyle style, bool static
 QVariant EffectsHandlerImpl::kwinOption(KWinOption kwopt)
 {
     switch (kwopt) {
-    case CloseButtonCorner:
+    case CloseButtonCorner: {
         // TODO: this could become per window and be derived from the actual position in the deco
-        return Decoration::DecorationBridge::self()->settings()->decorationButtonsLeft().contains(KDecoration2::DecorationButtonType::Close) ? Qt::TopLeftCorner : Qt::TopRightCorner;
+        const auto settings = Decoration::DecorationBridge::self()->settings();
+        return settings && settings->decorationButtonsLeft().contains(KDecoration2::DecorationButtonType::Close) ? Qt::TopLeftCorner : Qt::TopRightCorner;
+    }
     case SwitchDesktopOnScreenEdge:
         return ScreenEdges::self()->isDesktopSwitching();
     case SwitchDesktopOnScreenEdgeMovingWindows: