Include conditional for adding tag mods to connect channel (#1366)

* fix slug typo

* fix specs

* use blank? instead of nil?

app/labor/assign_tag_moderator.rb

@@ -4,7 +4,9 @@ module AssignTagModerator
       user = User.find(user_id)
       tag = Tag.find_by(name: tag_names[index])
       user.add_role(:tag_moderator, tag)
-      ChatChannel.find_by(slug: "tag-moderators").add_users(user)
+      if user.chat_channels.find_by(slug: "tag-moderators").blank?
+        ChatChannel.find_by(slug: "tag-moderators").add_users(user)
+      end
       NotifyMailer.tag_moderator_confirmation_email(user, tag.name).deliver unless tag.name == "go"
     end
   end