title: React Redux unexpected key passed to create store
body: <p>I am getting the error <code>Unexpected key "characters" found in initialState argument passed to createStore. Expected to find one of the known reducer keys instead: "marvelReducer", "routing". Unexpected keys will be ignored.</code> </p>
  
  <p>rootReducer : </p>
  
  <pre><code> import { combineReducers } from 'redux';
   import { routerReducer } from 'react-router-redux';
   import marvelReducer from './marvelReducer';
  
   const rootReducer = combineReducers({
     marvelReducer,
     routing: routerReducer
   });
   export default rootReducer;
  </code></pre>
  
  <p>marvelReducer : </p>
  
  <pre><code>import { FETCH_MARVEL } from '../constants/constants';
  import objectAssign from 'object-assign';
  
  export default function marvelReducer(state = [], action) {
    switch (action.type) {
      case FETCH_MARVEL:
        return objectAssign({}, state, {characters: action.data});
  
      default:
        return state;
    }
  }
  </code></pre>
  
  <p>store : </p>
  
  <pre><code>import { createStore } from 'redux';
  import { syncHistoryWithStore } from 'react-router-redux';
  import { browserHistory } from 'react-router';
  
  import rootReducer from '../reducers/index';
  
  const initialState = {
    characters: []
  };
  
  const store = createStore(rootReducer, initialState);
  
  export const history = syncHistoryWithStore(browserHistory, store);
  
  if (module.hot) {
    module.hot.accept('../reducers/', () =&gt; {
      const nextRootReducer = require('../reducers/index').default;
      store.replaceReducer(nextRootReducer);
    });
  }
  
  export default store;
  </code></pre>
  
  <p>I have very similar code in another application and it's working fine. Not sure what's going on here</p>