message: Only destroy ImGui context of != null
  Fixes
diff: @@ -51,8 +51,10 @@ namespace vks
  }
  UIOverlay::~UIOverlay() {
  + if (ImGui::GetCurrentContext()) {
  ImGui::DestroyContext();
  }
  + }
  /** Prepare all vulkan resources required to render the UI overlay */
  void UIOverlay::prepareResources()
  