title: Redux store does not have a valid reducer
body: <p>Haven't been able to find anything around here regarding this error:</p>
  
  <blockquote>
    <p>"Store does not have a valid reducer. Make sure the argument passed to combineReducers is an object whose values are reducers."</p>
  </blockquote>
  
  <p>My reducer</p>
  
  <pre><code>export default function FriendListReducer(state = {friends : []}, action) {
    switch (action.type) {
      case 'ADD_FRIEND':
        return [
          { friends : action.payload.friend }, ...state.friends
        ]     
      default:
        return state;
    }
    return state;
  }
  </code></pre>
  
  <p>Combiner</p>
  
  <pre><code>import { combineReducers } from 'redux';
  import { FriendListReducer } from './FriendListReducer';
  
  const rootReducer = combineReducers({
    friends: FriendListReducer
  });
  export default rootReducer;
  </code></pre>
  
  <p>My store config</p>
  
  <pre><code>import { applyMiddleware, createStore } from 'redux';
  import thunkMiddleware from 'redux-thunk';
  import createLogger from 'redux-logger';
  import rootReducer from '../reducers/reducers';
  
  export default function configureStore(initialState = { friends: [] }) {
    const logger = createLogger({
      collapsed: true,
      predicate: () =&gt;
      process.env.NODE_ENV === `development`, // eslint-disable-line no-unused-vars
    });
  
    const middleware = applyMiddleware(thunkMiddleware, logger);
  
    const store = middleware(createStore)(rootReducer, initialState);
  
    if (module.hot) {
      // Enable Webpack hot module replacement for reducers
      module.hot.accept('../reducers/reducers', () =&gt; {
        const nextRootReducer = require('../reducers/reducers').default;
        store.replaceReducer(nextRootReducer);
      });
    }
  
    return store;
  }
  </code></pre>