[컨텐츠][Bug] 컨텐츠 데이터 없을 경우 back -> error 수정

app/src/main/java/kr/co/zumo/app/lifeplus/view/screen/contents/ContentsFragment.java

@@ -228,7 +228,14 @@ public class ContentsFragment extends FragmentBase<ContentsPresenter> implements
 
   @Override
   public boolean dispatchBackPressed() {
+    if (null == layoutManager || null == recyclerViewContentsDetail) {
+      return false;
+    }
+
     ContentsHolder holder = (ContentsHolder) recyclerViewContentsDetail.findViewHolderForAdapterPosition(layoutManager.findFirstVisibleItemPosition());
+    if (null == holder) {
+      return false;
+    }
     return holder.dispatchBackPressed();
   }