我在Flutter项目中使用的是flutter_localizations。我需要将一些通用代码提取到本地程序包中，以供其他项目使用，因此我将在应用程序项目和程序包项目中使用.arb文件。
现在运行应用程序时，出现以下错误：
I/flutter ( 7637): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════
I/flutter ( 7637): The following assertion was thrown building Builder(dirty):
I/flutter ( 7637): type 'en' is not a subtype of type 'S'
I/flutter ( 7637):
I/flutter ( 7637): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter ( 7637): more information in this error message to help you determine and fix the underlying cause.
I/flutter ( 7637): In either case, please report this assertion by filing a bug on GitHub:
I/flutter ( 7637): https://github.com/flutter/flutter/issues/new
I/flutter ( 7637):
I/flutter ( 7637): When the exception was thrown, this was the stack:
I/flutter ( 7637): #0 _LocalizationsState.resourcesFor (package:flutter/src/widgets/localizations.dart:533:41)
I/flutter ( 7637): #1 Localizations.of (package:flutter/src/widgets/localizations.dart:445:39)
有人可以帮我吗？
谢谢。