add comment in JavaScript saying that component might be null

Author: timelyportfolio

srcjs/widget.js

@@ -91,6 +91,8 @@ export function reactWidget(name, type, components, options) {
                         }
                         lastValue = value;
                     }
+                    // with functional stateless components this will be null
+                    // see https://reactjs.org/docs/react-dom.html#render for more details
                     this.instance.component = ReactDOM.render(hydrate(components, value.tag), el);
                 });
             return {