How to use the scratch-gui.guiMiddleware function in scratch-gui

const parts = pathname.split('/').filter(Boolean);
    // parts[0]: 'projects'
    // parts[1]: either :id or 'editor'
    // parts[2]: undefined if no :id, otherwise either 'editor' or 'fullscreen'
    if (parts.indexOf('editor') === -1) {
        guiInitialState = GUI.initPlayer(guiInitialState);
    }
    if (parts.indexOf('fullscreen') !== -1) {
        guiInitialState = GUI.initFullScreen(guiInitialState);
    }
    return guiInitialState;
};

module.exports.guiReducers = GUI.guiReducers;
module.exports.guiInitialState = GUI.guiInitialState;
module.exports.guiMiddleware = GUI.guiMiddleware;
module.exports.initLocale = GUI.initLocale;
module.exports.localesInitialState = GUI.localesInitialState;

const mapDispatchToProps = dispatch => ({
    getProjectInfo: (id, token) => {
        dispatch(previewActions.getProjectInfo(id, token));
    }
});

module.exports.View = connect(
    mapStateToProps,
    mapDispatchToProps
)(EmbedView);

GUI.setAppElement(document.getElementById('app'));
module.exports.initGuiState = GUI.initEmbedded;
module.exports.guiReducers = GUI.guiReducers;
module.exports.guiInitialState = GUI.guiInitialState;
module.exports.guiMiddleware = GUI.guiMiddleware;
module.exports.initLocale = GUI.initLocale;
module.exports.localesInitialState = GUI.localesInitialState;

}
    return guiInitialState;
};

render(
    ,
    document.getElementById('app'),
    {
        preview: previewActions.previewReducer,
        ...GUI.guiReducers
    },
    {
        locales: GUI.initLocale(GUI.localesInitialState, window._locale),
        scratchGui: initGuiState(GUI.guiInitialState)
    },
    GUI.guiMiddleware
);