From 539f1c62528afed30e9ba5c6d792771798c556e5 Mon Sep 17 00:00:00 2001
From: Arpit Jalan <arpit@techapj.com>
Date: Wed, 21 Nov 2018 09:48:38 +0530
Subject: [PATCH] FIX: raise `Discourse::NotFound` unless the topic is present

---
 app/controllers/topics_controller.rb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index 12c1e99bf06..ae1ecff512d 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -501,9 +501,11 @@ class TopicsController < ApplicationController
     params.require(:username)
     topic = Topic.find_by(id: params[:topic_id])
     user = User.find_by(username: params[:username])
+
+    raise Discourse::NotFound unless topic
     guardian.ensure_can_remove_allowed_users!(topic, user)
 
-    if topic&.remove_allowed_user(current_user, user)
+    if topic.remove_allowed_user(current_user, user)
       render json: success_json
     else
       render json: failed_json, status: 422