yuzu: fix the stuck in fullscreen mode bug

Co-Authored-By: Valentin Vanelslande <vvanelslandedev@gmail.com>

src/yuzu/main.cpp

@@ -1034,6 +1034,14 @@ void GMainWindow::BootGame(const QString& filename) {
 }
 
 void GMainWindow::ShutdownGame() {
+    if (!emulation_running) {
+        return;
+    }
+
+    if (ui.action_Fullscreen->isChecked()) {
+        HideFullscreen();
+    }
+
     AllowOSSleep();
 
     discord_rpc->Pause();