"Cannot run with sound null safety" for package:isolate when doing "flutter run" without "--no-sound-null-safety"

[florianrein]

For Android & iOS, when I do flutter run, i get the following error message

Error output from Xcode build:
↳
** BUILD FAILED
Xcode's output:
↳
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:isolate

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

(Respectively the Android equivalent).

My flutter doctor output is the following:

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.0.5, on Mac OS X 10.15.4 19E287 darwin-x64, locale de-DE)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 4.0)
[✓] VS Code (version 1.55.2)
[✓] Connected device (2 available)

• No issues found!

It is fixed by applying --no-sound-null-safety. I'd like to suggest to at least add it to the readme.