fix a bug for OTA updating feature.

Add a help script to pack OTA package

src/slic3r/GUI/GUI_App.cpp

@@ -4789,6 +4789,7 @@ void GUI_App::start_sync_user_preset(bool with_progress_dlg)
         [this, progressFn, cancelFn, finishFn, t = std::weak_ptr<int>(m_user_sync_token)] {
             // get setting list, update setting list
             std::string version = preset_bundle->get_vendor_profile_version(PresetBundle::ORCA_DEFAULT_BUNDLE).to_string();
+            if(!m_agent) return;
             int ret = m_agent->get_setting_list2(version, [this](auto info) {
                 auto type = info[BBL_JSON_KEY_TYPE];
                 auto name = info[BBL_JSON_KEY_NAME];