Error: Method not found: 'TypeMatcher'

[ShaneyWaris]

/C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/calendarro-1.2.0/lib/calendarro.dart:81:41: Error: Method not found: 'TypeMatcher'.
context.ancestorStateOfType(const TypeMatcher());

I am a beginner in flutter development. And in one of the project, I am using calendarro library in a flutter. After importing this library, I am getting the error mentioned above. Can anyone help me to get rid of this error?

I am using flutter stable version 2.2.0

Note: This calendarro.dart file was itself giving me some errors initially because of date_utils.dart file present in it. As class name in this "date_utils.dart" file is DateUtils which also exist in the material library. So, I have just imported "date_utils.dart" file as "du" in calendarro.dart file and then use functions of "date_utils.dart" file accordingly in "calendarro.dart" file.

Thanks!