[오류처리] A RenderBox object must have an explicit size
아래와 같은 오류가 보인다면 ...
A RenderBox object must have an explicit size before it can be hit-tested. Make sure that the RenderBox in question sets its size during layout.
해결
shrinkWrap : true 를 추가하여 컨텐츠의 사이즈 정보를 추가하도록 한다