title: Missing "key" prop for element. (ReactJS and TypeScript)
body: <p>I am using below code for reactJS and typescript. While executing the commands I  get below error.</p>
  
  <p>I also added the import statement 
  import 'bootstrap/dist/css/bootstrap.min.css';
  in Index.tsx. </p>
  
  <p>Is there a way to fix this issue?</p>
  
  <pre><code>npm start
  
  client/src/Results.tsx
  (32,21): Missing "key" prop for element.
  </code></pre>
  
  <p>The file is as below "Results.tsx"</p>
  
  <pre><code>import * as React from 'react';
   class Results extends React.Component&lt;{}, any&gt; {
  
  constructor(props: any) {
      super(props);
  
      this.state = {
          topics: [],
          isLoading: false
      };
  }
  
  componentDidMount() {
      this.setState({isLoading: true});
  
      fetch('http://localhost:8080/topics')
          .then(response =&gt; response.json())
          .then(data =&gt; this.setState({topics: data, isLoading: false}));
  }
  
  render() {
      const {topics, isLoading} = this.state;
  
      if (isLoading) {
          return &lt;p&gt;Loading...&lt;/p&gt;;
      }
  
      return (
          &lt;div&gt;
              &lt;h2&gt;Results List&lt;/h2&gt;
              {topics.map((topic: any) =&gt;
                  &lt;div className="panel panel-default"&gt;
                      &lt;div className="panel-heading" key={topic.id}&gt;{topic.name}&lt;/div&gt;
                      &lt;div className="panel-body" key={topic.id}&gt;{topic.description}&lt;/div&gt;
                  &lt;/div&gt;
              )}
          &lt;/div&gt;
      );
  }
  }
  
  export default Results;
  </code></pre>