fix Alviss of the Nordic Alfar

https://www.db.yugioh-card.com/yugiohdb/faq_search.action?ope=4&cid=14065
（対象を取る効果ではありません。ダメージステップに発動する事はできません。）

c27024795.lua

@@ -17,7 +17,7 @@ function c27024795.initial_effect(c)
 	e2:SetDescription(aux.Stringid(27024795,1))
 	e2:SetCategory(CATEGORY_SPECIAL_SUMMON)
 	e2:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
-	e2:SetProperty(EFFECT_FLAG_DAMAGE_STEP+EFFECT_FLAG_DELAY)
+	e2:SetProperty(EFFECT_FLAG_DELAY)
 	e2:SetCode(EVENT_TO_GRAVE)
 	e2:SetRange(LOCATION_GRAVE)
 	e2:SetCountLimit(1,27024795+EFFECT_COUNT_CODE_DUEL)
@@ -72,11 +72,13 @@ function c27024795.spop(e,tp,eg,ep,ev,re,r,rp)
 		sg:Merge(g)
 	end
 	if Duel.SendtoGrave(sg,REASON_EFFECT)==3 then
-		Duel.BreakEffect()
 		Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
 		local tg=Duel.SelectMatchingCard(tp,c27024795.spfilter,tp,LOCATION_EXTRA,0,1,1,nil,e,tp)
+		if tg:GetCount()>0 then
+			Duel.BreakEffect()
 			Duel.SpecialSummon(tg,0,tp,tp,false,false,POS_FACEUP)
 		end
+	end
 end
 function c27024795.cfilter(c,tp)
 	return c:IsPreviousSetCard(0x4b) and c:GetPreviousControler()==tp