message: Fix potential null pointer crash
  Passing `-y` without specifying an IBL on the command line would lead to a crash.
diff: @@ -311,7 +311,7 @@ static void setup(Engine* engine, View* view, Scene* scene) {
  .color(Color::toLinear<ACCURATE>(sRGBColor{0.98f, 0.92f, 0.89f}))
  .intensity(110000.0f)
  .direction({0.6f, -1.0f, -0.8f})
  - .castShadows(true)
  + //.castShadows(true)
  .build(*engine, g_light);
  if (g_lightOn) {
  @@ -323,7 +323,8 @@ static void setup(Engine* engine, View* view, Scene* scene) {
  }
  if (!g_skyboxOn) {
  - FilamentApp::get().getIBL()->getSkybox()->setLayerMask(0xff, 0x00);
  + auto ibl = FilamentApp::get().getIBL();
  + if (ibl) ibl->getSkybox()->setLayerMask(0xff, 0x00);
  }
  view->setClearColor(Color::toLinear({
  