Hello,

I installed the gem ddtrace on my rails application and created the config file as the documentation says:

config/initializers/datadog-tracer.rb:

Datadog.configure do |c|
  c.use :rails
end

Gemfile.lock extract:

ddtrace (0.18.0)
      msgpack
      opentracing (>= 0.4.1)

If I attempt to access my active record models, event something like MyObject.count I receive the following error:

SystemStackError: stack level too deep
from /.rbenv/versions/2.4.3/lib/ruby/gems/2.4.0/gems/activesupport-5.0.7/lib/active_support/core_ext/object/json.rb:161:in `dup'

If I remove the config file or remove the line in the do-end block everything works again.