wayland: check screen isPlaceholder and if wl_output is null

Fixes crashes on disconnected monitors

changelog/next.md

@@ -46,6 +46,7 @@ set shell id.
 - Fixed asynchronous loaders not working before window creation.
 - Fixed memory leak in IPC handlers.
 - Fixed ClippingRectangle related crashes.
+- Fixed crashes when monitors are unplugged.
 
 ## Packaging Changes
 

src/wayland/session_lock/surface.cpp

@@ -28,7 +28,7 @@ QSWaylandSessionLockSurface::QSWaylandSessionLockSurface(QtWaylandClient::QWayla
 	wl_output* output = nullptr; // NOLINT (include)
 	auto* waylandScreen = dynamic_cast<QtWaylandClient::QWaylandScreen*>(qwindow->screen()->handle());
 
-	if (waylandScreen != nullptr) {
+	if (waylandScreen != nullptr && !waylandScreen->isPlaceholder() && waylandScreen->output()) {
 		output = waylandScreen->output();
 	} else {
 		qFatal() << "Session lock screen does not corrospond to a real screen. Force closing window";

src/wayland/wlr_layershell/surface.cpp

@@ -143,11 +143,11 @@ LayerSurface::LayerSurface(LayerShellIntegration* shell, QtWaylandClient::QWayla
 		auto* waylandScreen =
 		    dynamic_cast<QtWaylandClient::QWaylandScreen*>(qwindow->screen()->handle());
 
-		if (waylandScreen != nullptr) {
+		if (waylandScreen != nullptr && !waylandScreen->isPlaceholder() && waylandScreen->output()) {
 			output = waylandScreen->output();
 		} else {
 			qWarning()
-			    << "Layershell screen does not corrospond to a real screen. Letting the compositor pick.";
+			    << "Layershell screen does not correspond to a real screen. Letting the compositor pick.";
 		}
 	}