FAILURE: Build failed with an exception. C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/win32-2.3.6/lib/src/structs.g.dart: Error: Setter not found: 'UnicodeChar'. set UnicodeChar(int value) => Char.UnicodeChar = value; 'AsciiChar'. set AsciiChar(int value) => Char.AsciiChar = value;