Possibly fixing transforms.

src/xenia/gpu/gl4/gl4_graphics_system.cc

@@ -258,6 +258,10 @@ void GL4GraphicsSystem::SwapHandler(const SwapParameters& swap_params) {
   // Swap requested. Synchronously post a request to the loop so that
   // we do the swap in the right thread.
   control_->SynchronousRepaint([&]() {
+    if (!swap_params.framebuffer_texture) {
+      // no-op.
+      return;
+    }
     control_->context()->blitter()->BlitTexture2D(
         swap_params.framebuffer_texture, swap_params.x, swap_params.y,
         swap_params.width, swap_params.height, 0, 0, control_->width(),