render_exception

# File actionpack/lib/action_dispatch/middleware/debug_exceptions.rb, line 55
      def render_exception(request, exception)
        backtrace_cleaner = request.get_header("action_dispatch.backtrace_cleaner")
        wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
        log_error(request, wrapper)

        if request.get_header("action_dispatch.show_detailed_exceptions")
          begin
            content_type = request.formats.first
          rescue ActionDispatch::Http::MimeNegotiation::InvalidType
            content_type = Mime[:text]
          end

          if api_request?(content_type)
            render_for_api_request(content_type, wrapper)
          else
            render_for_browser_request(request, wrapper)
          end
        else
          raise exception
        end
      end