1、修改 StateLayout

lib/widget/state_layout.dart

@@ -15,7 +15,11 @@ class StateLayout extends StatefulWidget {
 class _StateLayoutState extends State<StateLayout> {
   @override
   Widget build(BuildContext context) {
-    return widget.type == StateType.loading ? _loadingWidget() : _otherWidget();
+    return SizedBox(
+      width: double.infinity,
+      child:
+          widget.type == StateType.loading ? _loadingWidget() : _otherWidget(),
+    );
   }
 
   Widget _loadingWidget() {