title: Create React App not showing error message with ErrorBoundary
body: <p>I'm learning how to use <code>componentDidCatch()</code>. It looks straight forward. It works, but to still show the complete error stack on view.</p>
  
  <p>In separate files:</p>
  
  <pre><code>import React, { Component } from 'react'
  
  class ErrorBoundary extends Component {
    constructor(props) {
      super(props);
      this.state = {
        hasError: false
      }
    }
  
    componentDidCatch(error, info) {
      console.log("Catching an error") // this is never logged
      this.setState(state =&gt; ({...state, hasError: true }))
    }
  
    render() {
      if (this.state.hasError) { return &lt;div&gt;Sorry, an error occurred&lt;/div&gt; }
  
      return this.props.children
    }
  }
  export default ErrorBoundary
  
        ...
  
  import React, { Component } from 'react'
  
  class Foo extends Component {
  
    render() {
      return this.props.a.b; // So this should cause the error
    }
  }
  export default Foo
  
        ...
  
  import React, { Component } from 'react'
  // Imported Foo and ErrorBoundary
  
  class Home extends Component {
  
    render() {
      return &lt;ErrorBoundary&gt;&lt;Foo /&gt;&lt;/ErrorBoundary&gt;
    }
  }
  export default Home
  </code></pre>
  
  <p>On page refresh, I see <code>Sorry, an error occurred</code> for, literally, a second then the full error stack displaying to the user. Is this an issue with Create React App? I'm using React 16.</p>