https://learn.microsoft.com/ja-jp/dotnet/api/system.windows.data.bindingexpressionbase.haserror?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
BindingExpressionBase.HasError Property (System.Windows.Data) | Microsoft Learn
Gets a value that indicates whether the parent binding has a failed validation rule.
property systemwindowsdatamicrosoftlearn
https://pub.dev/documentation/flutter_riverpod/latest/flutter_riverpod/AsyncValueExtensions/hasError.html
hasError property - AsyncValueExtensions extension - flutter_riverpod library - Dart API
API docs for the hasError property from the AsyncValueExtensions extension, for the Dart programming language.
propertyextensionflutterlibrarydart