title: I get this error: "'handleDelete' is not defined" after run `npm run build`
body: <p>Why did I get this error(after <code>npm run build</code>)? While <code>handleDelete</code> is defined.</p>
  <p><a href="https://i.stack.imgur.com/cjSfQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cjSfQ.png" alt="enter image description here" /></a></p>
  <p>BlogList.js:</p>
  <pre><code>const BlogList = ({blogs, title, handleDelete}) =&gt; {
      return(
          &lt;div className=&quot;blog-list&quot;&gt;
              &lt;h2&gt;{title}&lt;/h2&gt;
              {blogs.map((blog) =&gt; (
                  &lt;div className=&quot;blog-preview&quot; key={blog.id}&gt;
                      &lt;h2&gt;{blog.title}&lt;/h2&gt;
                      &lt;p&gt;Written by {blog.author}&lt;/p&gt;
                      &lt;button onClick={() =&gt; handleDelete(blog.id)}&gt;
                          Delete Blog
                      &lt;/button&gt;
                  &lt;/div&gt;
              ))}
          &lt;/div&gt;
      )
  }
  
  export default BlogList;
  </code></pre>
  <p>Home.js</p>
  <pre><code>import BlogList from &quot;./BlogList&quot;;
  
  const Home = () =&gt;{
      const [blogs, setBlogs] = useState([
          { title: 'My new website', body: 'lorem ipsum...', author: 'mario', id: 1 },
          { title: 'Welcome party!', body: 'lorem ipsum...', author: 'yoshi', id: 2 },
          { title: 'Web dev top tips', body: 'lorem ipsum...', author: 'mario', id: 3 }
      ]);
  
      const handleDelete = (id) =&gt; {
          const newBlogs = blogs.filter(blog =&gt; blog.id !== id);
          setBlogs(newBlogs);
      }
      return(
          &lt;div className=&quot;Home&quot;&gt;
              &lt;BlogList blogs={blogs} title=&quot;All Blogs&quot; handleDelete={handleDelete} /&gt;
          &lt;/div&gt;
      );
  }
  
  export default Home;
  </code></pre>