title: The preloadedState argument passed to createStore has unexpected type of "Null". Expected argument to be an object with the following keys: "login"
body: <p>Guys i am having trouble debugging the error i have recently got in my application, which is
  "The preloadedState argument to createStore has unexpected type of Null.Expected argument to be an object with the fillowing keys: "login""</p>
  
  <p>Here is a reducer file code snippet which export combinedReducers</p>
  
  <pre><code>import {Map, fromJS} from 'immutable';
  import {combineReducers} from 'redux';
  
  import { login } from '../modules/login/LoginReducer';
  
  export default combineReducers({
    login
  });
  </code></pre>
  
  <p>======================================</p>
  
  <h1>AND THE Login Reducer code snippet looks like</h1>
  
  <pre><code>import {
    AUTH_USER,
    SET_ADMIN_PRIVILEGES,
    AUTH_ERROR
  } from './login.types';
  
  const INITIAL_STATE = { errors: null, authenticated: false, admin_privileges: false };
  
  export const login =  (state = INITIAL_STATE, action) =&gt; {
   switch(action.type) {
       case AUTH_USER:
              return { ...state, errors: null, authenticated: true };
          case SET_ADMIN_PRIVILEGES:
              return { ...state, admin_privileges: true };
           case AUTH_ERROR:
              return { ...state, errors: action.errors };
            default:
              return state;
   }
  
  };
  </code></pre>
  
  <p>==============================</p>
  
  <h1>AND THE STORE</h1>
  
  <pre><code>import {applyMiddleware, createStore, compose} from 'redux';
  import * as reduxLoop from 'redux-loop';
  
  import middleware from './middleware';
  import reducer from './reducer';
  
  const enhancer = compose(
    applyMiddleware(...middleware),
    reduxLoop.install()
  );
  
  // create the store
  const store = createStore(
    reducer,
    null,
    enhancer
  );
  
  export default store;
  </code></pre>
  
  <p>========================
  Please help guys..</p>