Fix scrollIntoView undefined bug when there is no hash, fixes #114

Thanks to @kevin-buttercoin for this fix!

source/javascripts/app/lang.js

@@ -33,7 +33,9 @@ under the License.
     global.toc.calculateHeights();
 
     // scroll to the new location of the position
-    $(window.location.hash).get(0).scrollIntoView(true);
+    if ($(window.location.hash).get(0)) {
+      $(window.location.hash).get(0).scrollIntoView(true);
+    }
   }
 
   // if a button is clicked, add the state to the history