PromucFlow_constructor/app/client/src/index.tsx

import React from "react";
import ReactDOM from "react-dom";
import { Provider } from "react-redux";
import "./index.css";
import App from "./App";
import Editor from "./pages/Editor";
import PageNotFound from "./pages/PageNotFound";
import * as serviceWorker from "./serviceWorker";
import { BrowserRouter, Route, Switch } from "react-router-dom";
import { createStore, applyMiddleware } from "redux";
import appReducer from "./reducers";
import WidgetBuilderRegistry from "./utils/WidgetRegistry";
import { ThemeProvider, theme } from "./constants/DefaultTheme";
import createSagaMiddleware from 'redux-saga'
import { rootSaga } from "./sagas"
// import { ActionType, ReduxAction } from "./constants/ActionConstants";

import { DndProvider } from "react-dnd"
import HTML5Backend from "react-dnd-html5-backend"
import { appInitializer } from "./utils/AppsmithUtils";

appInitializer()
WidgetBuilderRegistry.registerWidgetBuilders();
const sagaMiddleware = createSagaMiddleware()
const store = createStore(appReducer, applyMiddleware(sagaMiddleware));
sagaMiddleware.run(rootSaga)
ReactDOM.render(

  <DndProvider backend={HTML5Backend}>
    <Provider store={store}>
      <ThemeProvider theme={theme}>
        <BrowserRouter>
          <Switch>
            <Route exact path="/" component={App} />
            <Route exact path="/builder" component={Editor} />
            <Route component={PageNotFound} />
          </Switch>
        </BrowserRouter>
      </ThemeProvider>
    </Provider>
  </DndProvider>,
  document.getElementById("root")
);

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: http://bit.ly/CRA-PWA
serviceWorker.unregister();