fix grey boxes on follow notifs

lib/business_logic/notifications/notifs.dart

@@ -15,6 +15,7 @@ class NotificationModel implements Comparable {
   late PostModel? post;
   late String? accountid;
   NotificationModel.fromJson(Map<String, dynamic> json) {
+    post = null;
     time = json["created_at"];
     id = json["id"];
     account = AccountModel.fromJson(json["account"]);