Fixing react warnings on permalink return

webapp/components/posts_view.jsx

@@ -384,6 +384,7 @@ export default class PostsView extends React.Component {
     }
     componentWillUnmount() {
         window.removeEventListener('resize', this.handleResize);
+        this.scrollStopAction.cancel();
     }
     componentDidUpdate() {
         if (this.props.postList != null) {