Don't use 'BuildContext's across async gaps – where does the mounted property come from?

How to rewrite this to awoid Don't use 'BuildContext's across async gaps. warning.

onPressed: () async {
  if (snapshot.hasData) {
    final isRapportExist = await bloc.isRapportExist();

    if (isRapportExist) {
      return;
    }

    bloc.submitRapport();
    Navigator.pop(context, true); //Don't use 'BuildContext's across async gaps.
  }
},

In such cases usully mounted property used, but where it comes from?

if(!mounted) return; //Undefined name 'mounted'.
Navigator.pop(context, true);

>Solution :

It’s a property of the State class – which your State extends.

https://api.flutter.dev/flutter/widgets/State-class.html