You are setting a key that conflicts with a built-in method Slack::Messages::Message#presence defined at /app/vendor/bundle/ruby/2.3.0/gems/slack-ruby-client-0.7.8/lib/slack/messages/message.rb:4. This can cause unexpected behavior when accessing the key via as a property. You can still access the key via the #[] method. #132
This is because of Hashie 3.5.0, see hashie/hashie#394