render_exception

# File actionpack/lib/action_dispatch/middleware/debug_exceptions.rb, line 32
    def render_exception(env, exception)
      wrapper = ExceptionWrapper.new(env, exception)
      log_error(env, wrapper)

      if env['action_dispatch.show_detailed_exceptions']
        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
          :request => Request.new(env),
          :exception => wrapper.exception,
          :application_trace => wrapper.application_trace,
          :framework_trace => wrapper.framework_trace,
          :full_trace => wrapper.full_trace
        )

        file = "rescues/#{wrapper.rescue_template}"
        body = template.render(:template => file, :layout => 'rescues/layout')
        render(wrapper.status_code, body)
      else
        raise exception
      end
    end