Error boundaries docs shouldn't use class fields

content/docs/error-boundaries.md

@@ -150,14 +150,15 @@ React doesn't need error boundaries to recover from errors in event handlers. Un
 
 If you need to catch an error inside event handler, use the regular JavaScript `try` / `catch` statement:
 
-```js{8-12,16-19}
+```js{9-13,17-20}
 class MyComponent extends React.Component {
   constructor(props) {
     super(props);
     this.state = { error: null };
+    this.handleClick = this.handleClick.bind(this);
   }
 
-  handleClick = () => {
+  handleClick() {
     try {
       // Do something that could throw
     } catch (error) {