cannot use proper named parameter in flutter app

Question

yes, i did just do that.

the trouble i have is that i can't remove the red underline, and thus my project won't run. InputDecoration error parameter : https://api.flutter.dev/flutter/material/InputDecoration/error.html

defintely exists .. the other named parameters work.

I'll leave it at this. It's quite straightforward ! and nothing to help me elsewhere online .. yes, i tried flutter doctor, clean, whatever.