title: Flatlist unique "key" pop warning
body: <p>With my flatlist I get this message no matter what I try.</p>
  <blockquote>
  <p>Warning: Each child in a list should have a unique &quot;key&quot; prop.</p>
  </blockquote>
  <p>I don't have this issue when my data is a simple array.</p>
  <pre><code>const raceClass = &lt;View style={[styles.countdownBoxes, styles.cdown]}&gt;
      &lt;Text style={[styles.titleText, styles.item]}&gt;Race&lt;/Text&gt;{timerComponents.length ? timerComponents : &lt;Text&gt;Time's up!&lt;/Text&gt;}
  &lt;/View&gt;;
  const deadlineClass = &lt;View style={[styles.countdownBoxes, styles.dline]}&gt;
      &lt;Text style={[styles.titleText, styles.item]}&gt;Deadline&lt;/Text&gt;{timerComponentsDeadline.length ? timerComponentsDeadline : &lt;Text&gt;Time's up!&lt;/Text&gt;}
  &lt;/View&gt;;
  
  const flatListItems = [
      { title: &quot;raceCountdown&quot;, text: &quot;Race&quot;, content: raceClass, styleClasses: &quot;styles.cdown&quot; },
      { title: &quot;deadlineCountdown&quot;, text: &quot;Deadline&quot;, content: deadlineClass, styleClasses: &quot;styles.dline&quot; }
  ]
  return (
      &lt;View style={styles.timeContainer}&gt;
          &lt;FlatList
          data={flatListItems}
          numColumns={2}
          keyExtractor={(flatListItems) =&gt; {flatListItems.title}}
          renderItem={({ item }) =&gt; (
              &lt;View style={styles.boxContainer}&gt;
                  {item.content}
              &lt;/View&gt;
          )} /&gt;
      &lt;/View&gt;
  )
  </code></pre>