Don't call discourse hub during user destroy if hub integration is disabled

lib/user_destroyer.rb

@@ -20,7 +20,7 @@ class UserDestroyer
       user.destroy.tap do |u|
         if u
           AdminLogger.new(@admin).log_user_deletion(user)
-          DiscourseHub.unregister_nickname(user.username)
+          DiscourseHub.unregister_nickname(user.username) if SiteSetting.call_discourse_hub?
           MessageBus.publish "/file-change", ["refresh"], user_ids: [user.id]
         end
       end

spec/components/user_destroyer_spec.rb

@@ -86,10 +86,17 @@ describe UserDestroyer do
           destroy
         end
 
-        it 'should unregister the nickname as the discourse hub' do
+        it 'should unregister the nickname as the discourse hub if hub integration is enabled' do
+          SiteSetting.stubs(:call_discourse_hub?).returns(true)
           DiscourseHub.expects(:unregister_nickname).with(@user.username)
           destroy
         end
+
+        it 'should not try to unregister the nickname as the discourse hub if hub integration is disabled' do
+          SiteSetting.stubs(:call_discourse_hub?).returns(false)
+          DiscourseHub.expects(:unregister_nickname).never
+          destroy
+        end
       end
 
       context 'and destroy fails' do