Cannot run with sound null safety

flutter sdk 版本升级到2.0或者更高的版本后，运行之前的代码会报错，比如：

Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:flutter_swiper
 - package:flutter_page_indicator
 - package:transformer_page_view

For solutions, see https://dart.dev/go/unsound-null-safety


FAILURE: Build failed with an exception.

上面的问题是，这些包不支持 safety模式。我们可以在运行的时候添加--no-sound-null-safety。打开Android Studio，然后依次选择【Run】 -->【 Edit Configurations】 --> 【Add Additional Run args 】--> 【--no-sound-null-safety】，如下图。

然后，再次运行就没有错误了。