From 5a6e5a401291349b746ba2d5d24f0d148ae3d7f4 Mon Sep 17 00:00:00 2001
From: Selase Krakani <849886+s3lase@users.noreply.github.com>
Date: Thu, 16 Feb 2023 10:47:01 +0000
Subject: [PATCH] FIX: Unsubscribing via key associated with deleted topic
 (#20275)

Currently, clicking on the unsubscribe link with a `key` associated with a
deleted topic results in an HTTP 500 response.

This change fixes that by skipping any attempt to run topic related flow if topic
isn't present.
---
 lib/email_controller_helper/topic_email_unsubscriber.rb | 2 ++
 spec/requests/email_controller_spec.rb                  | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/lib/email_controller_helper/topic_email_unsubscriber.rb b/lib/email_controller_helper/topic_email_unsubscriber.rb
index eda37b7d667..e31ef94e1b0 100644
--- a/lib/email_controller_helper/topic_email_unsubscriber.rb
+++ b/lib/email_controller_helper/topic_email_unsubscriber.rb
@@ -8,6 +8,8 @@ module EmailControllerHelper
 
       topic = unsubscribe_key.associated_topic
 
+      return if topic.blank?
+
       controller.instance_variable_set(:@topic, topic)
       controller.instance_variable_set(
         :@watching_topic,
diff --git a/spec/requests/email_controller_spec.rb b/spec/requests/email_controller_spec.rb
index 57478f38fe5..c9c29a0d0cb 100644
--- a/spec/requests/email_controller_spec.rb
+++ b/spec/requests/email_controller_spec.rb
@@ -317,6 +317,15 @@ RSpec.describe EmailController do
         expect(response.body).not_to include("unwatch_category")
       end
 
+      it "displays form even if topic is deleted" do
+        post.topic.trash!
+
+        navigate_to_unsubscribe
+
+        expect(response.status).to eq(200)
+        expect(response.body).to include(I18n.t("unsubscribe.all", sitename: SiteSetting.title))
+      end
+
       def create_category_user(notification_level)
         CategoryUser.create!(
           user_id: user.id,