video: NULL-check display in SDL_DestroyWindow

src/video/SDL_video.c

@@ -3360,7 +3360,7 @@ void SDL_DestroyWindow(SDL_Window *window)
     }
 
     display = SDL_GetDisplayForWindow(window);
-    if (display->fullscreen_window == window) {
+    if (display && display->fullscreen_window == window) {
         display->fullscreen_window = NULL;
     }