use provider inside initstate
@override
void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      auth = Provider.of<Auth>(context, listen: false);
    });
}
################ OR
@override
void initState() {
  super.initState();
  
  Future.delayed(Duration.zero,() {
    //Do your stuff here
  });
}
