fix: 분실물 상태 null 방어 처리

Author: d6nggyun

src/main/java/_ITHON/ReturnZone/domain/chat/dto/res/ChatRoomResponseDto.java

@@ -46,6 +46,6 @@ public ChatRoomResponseDto(ChatRoom chatRoom, Member otherMember, String lastMes
         this.lastMessage = lastMessage;
         this.lastMessageAt = chatRoom.getLastMessageAt();
         this.unreadCount = unreadCount;
-        this.lostPostStatus = lostPostStatus.getDescription();
+        this.lostPostStatus = lostPostStatus != null ? lostPostStatus.getDescription() : null;
     }
 }