🐛 fix: 알림 거래가, 목표가 타입 변경

packages/frontend/src/components/ui/alarm/Alarm.tsx

@@ -3,7 +3,7 @@ import Flag from '@/assets/flag.svg?react';
 
 export interface AlarmProps {
   option: string;
-  goalPrice: number | string;
+  goalPrice: number;
   alarmDate: string | null;
 }
 

packages/frontend/src/pages/stock-detail/NotificationPanel.tsx

@@ -36,14 +36,18 @@ const NotificationContents = () => {
   }
 
   if (!data) {
+    return <p className="text-center">알림 정보를 불러오는 데 실패했어요.</p>;
+  }
+
+  if (data.length === 0) {
     return <p className="text-center">현재 설정된 알림이 없어요.</p>;
   }
 
   return data.map((alarm) => (
     <Alarm
       key={alarm.alarmId}
       option={alarm.targetPrice ? '목표가' : '거래가'}
-      goalPrice={alarm.targetPrice ?? alarm.targetVolume!}
+      goalPrice={alarm.targetPrice ?? alarm.targetVolume ?? 0}
       alarmDate={alarm.alarmExpiredDate}
     />
   ));