dont markAsRead for guests

public/src/client/topic/posts.js

@@ -202,7 +202,9 @@ define('forum/topic/posts', [
 					done();
 				});
 			} else {
+				if (app.uid) {
 					socket.emit('topics.markAsRead', [tid]);
+				}
 				navigator.update();
 				done();
 			}