title: React-Redux - No reducer provided for key "coins"
body: <p>Not sure why I'm getting the following errors.</p>
  
  <p>I'm just setting up my store, actions and reducers, I haven't called dispatch on anything yet.</p>
  
  <h3>Expected</h3>
  
  <p>App runs fine, Redux state is not updated</p>
  
  <h3>Results</h3>
  
  <p><a href="https://i.stack.imgur.com/iGupu.png" rel="noreferrer"><img src="https://i.stack.imgur.com/iGupu.png" alt="enter image description here"></a></p>
  
  src/index.js
  
  <pre><code>import React from 'react'
  import ReactDOM from 'react-dom'
  
  import { createStore, applyMiddleware, compose } from 'redux'
  import { Provider } from 'react-redux'
  import thunk from 'redux-thunk'
  import reducer from './reducer'
  
  import App from './App'
  import css from './coinhover.scss'
  
  const element = document.getElementById('coinhover');
  
  const store = createStore(reducer, compose(
      applyMiddleware(thunk),
      window.__REDUX_DEVTOOLS_EXTENSION__ &amp;&amp; window.__REDUX_DEVTOOLS_EXTENSION__()
  ));
  
  ReactDOM.render(
      &lt;Provider store={ store }&gt;
          &lt;App /&gt;
      &lt;/Provider&gt;, element);
  </code></pre>
  
  src/reducer/index.js
  
  <pre><code>import { combineReducers } from 'redux'
  import { coins } from './coins'
  
  export default combineReducers({
      coins
  });
  </code></pre>
  
  src/reducer/actions/coins.js
  
  <pre><code>import * as api from '../../services/api'
  import { storage, addToPortfolio } from '../../services/coinFactory'
  
  export const ADD_COIN = 'ADD_COIN'
  
  export function getCoin(coin) {
      return dispatch =&gt; {
          api.getCoin(coin)
              .then((res_coin)  =&gt; addToPortfolio(res_coin))
              .then((portfolio) =&gt; dispatch(updatePortfolio(portfolio)));
      }
  }
  
  export function updatePortfolio(portfolio) {
      return {
          type: ADD_COIN,
          portfolio
      }
  }
  </code></pre>
  
  finally src/reducer/coins/index.js
  
  <pre><code>import { ADD_COIN } from './actions'
  
  const initialState = [];
  
  export default (state = initialState, action) =&gt; {
      switch(action.type) {
          case ADD_COIN:
              return action.portfolio;
          default:
              return state;
      }
  }
  </code></pre>