Basic redux actions handling with multiple reducers

redux-basics.js

import { applyMiddleware, combineReducers, createStore } from 'redux';

//////////////////////////////////////////////////////

const userReducer = (state={}, action) => {
  switch (action.type) {
    case 'CHANGE_NAME': {
      return {...state, name: action.payload}
    }
    case 'CHANGE_AGE': {
      return {...state, age: action.payload}
    }
    case 'ADD_TWEET': {
      return {...state, tweets: !state.tweets ? 1 : state.tweets + 1 }
    }
    default: return state;
  }
};

//////////////////////////////////////////////////////

const tweetsReducer = (state=[], action) => {
  switch (action.type) {
    case 'ADD_TWEET': {
      return state.concat([action.payload]);
    }
    case 'ERROR': {
      throw Error('Error occured..');
    }
    default: return state;
  }
};

//////////////////////////////////////////////////////
// basic middleware

const logger = (store) => (next) => (action) => {
  console.log('action fired', action);
  next(action);
};

const error = (store) => (next) => (action) => {
  try {
    next(action);
  } catch(e) {
    console.error('Error came in..');
  }
};

//////////////////////////////////////////////////////

const reducers = combineReducers({
  user: userReducer,
  tweets: tweetsReducer
});

//////////////////////////////////////////////////////

const middleware = applyMiddleware(logger, error);
const store = createStore(reducers, middleware);

store.subscribe(() => {
  console.log(store.getState());
});

//////////////////////////////////////////////////////

console.log(store.getState());
store.dispatch({type: 'CHANGE_NAME', payload: 'Sancau'});
store.dispatch({type: 'CHANGE_AGE', payload: 29});
store.dispatch({type: 'ADD_TWEET', payload: {title: 'ASDASD'} });
store.dispatch({type: 'ERROR', payload: {title: 'ASDASD'} });