# File lib/ruote/engine.rb, line 124
    def replay_at_error (err)

      msg = err.msg.dup
      action = msg.delete('action')

      msg['replay_at_error'] = true
        # just an indication

      if msg['tree'] && fei = msg['fei']
        #
        # nukes the expression in case of [re]apply
        #
        exp = Ruote::Exp::FlowExpression.fetch(@context, fei)
        exp.unpersist_or_raise if exp
      end

      @context.storage.delete(err.to_h) # remove error

      @context.storage.put_msg(action, msg) # trigger replay
    end