When I try to use google_fonts I get an error like this. I also imported the library and added " google_fonts: ^3.0.1" to the "pub.yml" file.
" I added.

void main() {
  runApp(BenimUyg());
}

class BenimUyg extends StatelessWidget {
  const BenimUyg({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        backgroundColor: Colors.brown[300],
        body: SafeArea(
          child: Center(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: const <Widget>[
                CircleAvatar(
                  backgroundColor: Colors.lime,
                  backgroundImage: AssetImage("assets/images/kahve.jpg"),
                  radius: 70,
                ),
                Text(
                  "Flutter Kahvecisi",
                  style: TextStyle(
                    fontSize: 40,
                    fontFamily: "Courgette",
                    color: Colors.brown,
                  ),
                ),
                // ignore: unnecessary_const
                Text(
                  "Çok Yakındasınız",
                  style: GoogleFonts.pacifico(
                    textStyle: TextStyle(
                      color: Colors.lime,
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

>Solution :

The issue is coming from children: const <Widget>[ remove const.

 child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[ // here
                CircleAvatar(
                  backgroundColor: Colors.lime,
                  backgroundImage: AssetImage("assets/images/kahve.jpg"),
                  radius: 70,
                ),

class BenimUyg extends StatelessWidget {
  const BenimUyg({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        backgroundColor: Colors.brown[300],
        body: SafeArea(
          child: Center(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                const CircleAvatar(
                  backgroundColor: Colors.lime,
                  backgroundImage: AssetImage("assets/images/kahve.jpg"),
                  radius: 70,
                ),
                const Text(
                  "Flutter Kahvecisi",
                  style: TextStyle(
                    fontSize: 40,
                    fontFamily: "Courgette",
                    color: Colors.brown,
                  ),
                ),
                // ignore: unnecessary_const
                Text(
                  "Çok Yakındasınız",
                  style: GoogleFonts.pacifico(
                    textStyle: const TextStyle(
                      color: Colors.lime,
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}