1、优化ListView的Controller

lib/widget/my_refresh_list_public.dart

@@ -204,7 +204,7 @@ class _MyListViewPublicState extends State<MyListViewPublic> {
 }
 
 class MyListController {
-  late _MyListViewPublicState _deerListViewState;
+  _MyListViewPublicState? _deerListViewState;
 
   // 绑定状态
   void _bindEasyRefreshState(_MyListViewPublicState state) {
@@ -213,17 +213,17 @@ class MyListController {
 
   //刷新
   void callRefresh() {
-    _deerListViewState.callRefresh();
+    _deerListViewState?.callRefresh();
   }
 
   // 移除数据
   void removeItem(index) {
-    return _deerListViewState.removeItem(index);
+    return _deerListViewState?.removeItem(index);
   }
 
   // 刷新单个数据
   void notifySingleItem(index, beanJson) {
-    return _deerListViewState.notifySingleItem(index, beanJson);
+    return _deerListViewState?.notifySingleItem(index, beanJson);
   }
 }