我正在尝试创建我的第一个Flutter-Web项目？ 当我运行命令“ flutter package upgrade”时，它给了我一个错误：
flutter软件包升级
F:\Project\VSCode\progress>flutter packages upgrade
Could not find a file named "packages/flutter_web/pubspec.yaml" in https://github.com/flutter/flutter_web 7a4c33425ddd78c54aba07d86f3f9a4a0051769b.
Running "flutter packages upgrade" in progress...
pub upgrade failed (1)