我在跑步

> dart pub outdated --mode=null-safety

Showing dependencies that are currently not opted in to null-safety.
[✗] indicates versions without null safety support.
[✓] indicates versions opting in to null safety.

All your dependencies declare support for null-safety.

> dart pub upgrade --null-safety
No dependencies changed.
1 package is discontinued.
148 packages have newer versions incompatible with dependency constraints.
Try `dart pub outdated` for more information.

No changes to pubspec.yaml!

> dart pub get

然后运行dart migrate，得到以下输出：

Analyzing project...
[---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\]Bad state: Error: package has unmigrated dependencies.

Before migrating your package, we recommend ensuring that every library it
imports (either directly or indirectly) has been migrated to null safety, so
that you will be able to run your unit tests in sound null checking mode.  You
are currently importing the following non-null-safe libraries:

(a list of files of my project like: package:opengames/presentation/widgets/not_found_screen.dart)

Please upgrade the packages containing these libraries to null safe versions
before continuing.  To see what null safe package versions are available, run
the following command: `dart pub outdated --mode=null-safety`.

To skip this check and try to migrate anyway, re-run with the flag
`--skip-import-check`.

为什么会这样？我已经运行了dart pub outdated --mode=null-safety