fixed focus repeating every 500ms

components/CustomHeader.js

     };
 
     componentDidMount() {
-        if (this.refs.searchInput !== undefined && this.props.shouldFocusSearchBar) {
+        if (this.refs.searchInput !== undefined && this.refs.searchInput._root !== undefined && this.props.shouldFocusSearchBar) {
             // does not work if called to early for some reason...
-            setInterval(() => this.refs.searchInput._root.focus(), 500);
+            setTimeout(() => this.refs.searchInput._root.focus(), 500);
         }
     }