Fix/panel npe 버그 수정

src/main/java/com/example/cp_main_be/domain/home/service/HomeService.java

@@ -166,12 +166,18 @@ public PannelResponseDTO getPannelData(User user) {
     LocalDateTime startOfDay = LocalDate.now().atStartOfDay();
     LocalDateTime endOfDay = LocalDate.now().atTime(23, 59, 59);
 
-    Diary diary = diaryService.findMyDiaries(user).get(0);
+    Diary diary =
+        diaryRepository.findTodayDiaryByUser(user, startOfDay, endOfDay).stream()
+            .findFirst()
+            .orElse(null);
+
     if (diary != null && diary.getCreatedAt().isAfter(LocalDate.now().atStartOfDay())) {
       isDiaryCompleted = true;
     }
     UserQuiz userQuiz =
-        userQuizRepository.findAllTodayUserQuizByUser(user, startOfDay, endOfDay).get(0);
+        userQuizRepository.findAllTodayUserQuizByUser(user, startOfDay, endOfDay).stream()
+            .findFirst()
+            .orElse(null);
     if (userQuiz != null && userQuiz.getIsCompleted()) { // 오늘의 퀴즈 성공시
       isQuizCompleted = true;
     }

src/main/java/com/example/cp_main_be/domain/mission/diary/domain/repository/DiaryRepository.java

@@ -2,6 +2,7 @@
 
 import com.example.cp_main_be.domain.member.user.domain.User;
 import com.example.cp_main_be.domain.mission.diary.domain.Diary;
+import java.time.LocalDateTime;
 import java.util.List;
 import java.util.Optional;
 import org.springframework.data.domain.Pageable;
@@ -29,4 +30,12 @@ List<Diary> findByUserInAndIsPublicIsTrueAndUser_IdNotIn(
           + "LEFT JOIN FETCH c.writer cw " // 댓글 작성자 fetch
           + "WHERE d.id = :diaryId")
   Optional<Diary> findByIdWithDetails(@Param("diaryId") Long diaryId);
+
+  @Query(
+      "SELECT d FROM Diary d "
+          + "WHERE d.user = :user AND d.createdAt BETWEEN :startDate AND :endDate")
+  List<Diary> findTodayDiaryByUser(
+      @Param("user") User user,
+      @Param("startDate") LocalDateTime startDate,
+      @Param("endDate") LocalDateTime endDate);
 }