修改最新的flutter兼容版本

lib/main_page.dart

@@ -351,12 +351,12 @@ class _MainPage extends State<MainPage> with WidgetsBindingObserver {
     } else {
       pushData = sharedPreferences.getString("pushData") ?? "";
     }
-    if (pushData == null || pushData == "") return;
-    Map<String, dynamic> pushMap = jsonDecode(pushData);
+    if (pushData == "") return;
+    Map<String, dynamic>? pushMap = jsonDecode(pushData);
     if (pushMap != null) {
       String routeName = "";
       Map<String, dynamic> params = {};
-      switch (pushMap["typed"].toString()) {
+      switch (pushMap["typed"] ?? '') {
         case "1":
         case "ARTICLE":
           routeName = "/router/web_page";