NoMethodError: undefined method `ref' for nil:NilClass

https://sentry.gitlab.net/gitlab/gitlabcom/issues/1060455/

NoMethodError: undefined method `ref' for nil:NilClass
Did you mean?  def
  action_controller/metal/rendering.rb:29:in `map'
    self.formats = request.formats.map(&:ref).compact
  action_controller/metal/rendering.rb:29:in `process_action'
    self.formats = request.formats.map(&:ref).compact
  abstract_controller/callbacks.rb:42:in `block in process_action'
    super
  active_support/callbacks.rb:109:in `block in run_callbacks'
    env.value = !env.halted && (!block_given? || yield)
  gitlab/ip_address_state.rb:10:in `with'
    yield
...
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NoMethodError: undefined method `ref' for nil:NilClass
Did you mean?  def