# File lib/ruote/svc/error_handler.rb, line 158
    def deflate(err, fei, fexp=nil)

      return err unless err.respond_to?(:backtrace)

      fexp ||=
        Ruote::Exp::FlowExpression.dummy('fei' => fei, 'original_tree' => nil)

      fexp.deflate(err)
    end