`Error: Couldn't find constructor 'FormzInput._'.` when running `flutter test`

[Mohammed Anas]

So I'm using formz 0.4.0 in my project (great library, thanks!), but recently I'm starting to get these errors when running flutter test (I changed my Flutter directory to $FLUTTER for privacy reasons):

$FLUTTER/.pub-cache/hosted/pub.dartlang.org/formz-0.4.0/lib/formz.dart:96:36: Error: Couldn't find constructor 'FormzInput._'.
  const FormzInput.pure(T value) : this._(value);
                                   ^^^^
$FLUTTER/.pub-cache/hosted/pub.dartlang.org/formz-0.4.0/lib/formz.dart:99:37: Error: Couldn't find constructor 'FormzInput._'.
  const FormzInput.dirty(T value) : this._(value, false);

I suspect that this might be a bug in Dart, but I thought I'd ask here first. Do you have any idea about the cause and how to fix this?

These errors were produced on a macOS Big Sur machine, with Flutter 2.0.6 and Dart 2.12.3.

[Mohammed Anas]

Sorry, duplicate of #28.