Don't enqueue topic webhook unless a post has a topic

config/initializers/012-web_hook_events.rb

@@ -18,8 +18,13 @@ end
 end
 
 DiscourseEvent.on(:post_edited) do |post, topic_changed|
+  if post.topic
     WebHook.enqueue_post_hooks(:post_edited, post)
-  WebHook.enqueue_topic_hooks(:topic_edited, post.topic) if post.is_first_post? && topic_changed
+
+    if post.is_first_post? && topic_changed
+      WebHook.enqueue_topic_hooks(:topic_edited, post.topic)
+    end
+  end
 end
 
 %i(

spec/models/web_hook_spec.rb

@@ -145,6 +145,24 @@ describe WebHook do
       end
     end
 
+    describe 'when topic has been deleted' do
+      it 'should not enqueue a post/topic edited hooks' do
+        topic.trash!
+        post.reload
+
+        PostRevisor.new(post, topic).revise!(
+          post.user,
+          {
+            category_id: Category.last.id,
+            raw: "#{post.raw} new"
+          },
+          {}
+        )
+
+        expect(Jobs::EmitWebHookEvent.jobs.count).to eq(0)
+      end
+    end
+
     it 'should enqueue the right hooks for post events' do
       Fabricate(:web_hook)
 
@@ -188,7 +206,7 @@ describe WebHook do
     end
 
     it 'should enqueue the right hooks for user events' do
-      _user_web_hook = Fabricate(:user_web_hook, active: true)
+      Fabricate(:user_web_hook, active: true)
 
       Sidekiq::Testing.fake! do
         user