title: React+Redux - Expected the reducer to be a function
body: <p>I'm trying to implement redux in my universal app, but I've some problems with redux.
  I've this configureStore function:</p>
  
  <pre><code>import { createStore, applyMiddleware, compose } from 'redux';
  import thunkMiddleware from 'redux-thunk';
  import createLogger from 'redux-logger'
  import rootReducer from '../reducers/index';
  import { routerMiddleware } from 'react-router-redux';
  
  export default function configureStore(history, initialState) {
    const reduxRouterMiddleware = routerMiddleware(history);
    let finalCreateStore;
  
    if (__DEVELOPMENT__ &amp;&amp; __CLIENT__ &amp;&amp; __DEVTOOLS__) {
      const { persistState } = require('redux-devtools');
      const DevTools = require('../containers/DevTools/DevTools');
  
      finalCreateStore = compose(
        applyMiddleware(thunkMiddleware)(createStore),
        window.devToolsExtension ? window.devToolsExtension() : DevTools.instrument(),
        persistState(window.location.href.match(/[?&amp;]debug_session=([^&amp;]+)\b/))
      )(createStore);
    }
    else {
      finalCreateStore = applyMiddleware(thunkMiddleware)(createStore);
    }
  
    const store = finalCreateStore(rootReducer, initialState);
  
    if (__DEVELOPMENT__ &amp;&amp; module.hot) {
      module.hot.accept(rootReducer, () =&gt; {
        store.replaceReducer(rootReducer);
      });
    }
  
    return store;
  }
  </code></pre>
  
  <p>And then I've my rootReducer file that looks like this:</p>
  
  <pre><code>import { combineReducers } from 'redux';
  import environment from './environment';
  import general from './general';
  import alert from './alert';
  import user from './user';
  import { routerReducer } from 'react-router-redux'
  
  
  const rootReducer = combineReducers({
    environment,
    general,
    alert,
    user,
    routing: routerReducer
  });
  
  export default rootReducer;
  </code></pre>
  
  <p>The problem is that I get this error: Expected the reducer to be a function.
  I've googled and searched on StackOverflow(where there are some similar problems), but the answers doesn't works in my case.</p>
  
  <p>So, what I'm doing wrong ? and why ?</p>
  
  <p>Thanks.</p>