title: Loop inside loop in redux store
body: <p>I have a simple state:</p>
  <pre><code>const INITIAL_PEOPLE = {
      name: 'Friends',
      list: [
          {
              id: 1,
              name: 'Alexander',
              child: [
                  {
                      id: 2,
                      name: 'Romuald'
                  },
                  {
                      id: 3,
                      name: 'Vanessa'
                  }
              ]
          },
          {
              id: 4,
              name: 'Alex',
              child: [
                  {
                      id: 5,
                      name: 'Jessica'
                  }
  
              ]
          }
      ]
  }
  </code></pre>
  <p>Now I want to print that. Look at my code</p>
  <pre><code> {prople.list.map(person =&gt;
       &lt;li key={person.id}&gt;{person.name}
           {person.child.map(child =&gt;
               {child.name}
            )}
       &lt;/li&gt;
   )}
  </code></pre>
  <p>First loop works correctly but if I added second loop (child), console catch an error that person.child is undefined. Why it doesn't work?</p>