store.js

import { createStore, combineReducers, applyMiddleware } from 'redux';
// import thunk from "redux-thunk";

const reducer = (state = {}, action) => {
  switch (action.type) {
    case 'HI_': {
      debugger
      return {
        ...state,
        hi: 'hi'
      }
    }

    default: return state
  }
}

const reducers = combineReducers({
  reducer
});

export function configureStore(initialState = {}) {
    const rootReducer = reducers;
    const store = createStore(
        rootReducer,
        initialState,
        // applyMiddleware(thunk)
    );

    if (module.hot) {
        module.hot.accept(reducers, () => {
            const nextRootReducer =reducers;
            store.replaceReducer(nextRootReducer);
        });
    }

    return store;
}