My code snippet is as follows for an elevated button:

 onPressed: () async {
                                                                          var docRef = await context
                                                                              .read<FirestoreRepository>()
                                                                              .firestore
                                                                              .collection('users')
                                                                              .doc(userData.selfRef.id)
                                                                              .collection('checkout_sessions')
                                                                              .add({
                                                                            'price':
                                                                                pricePlans.first.selfRef.id,
                                                                            'success_url':
                                                                                'https://success.com',
                                                                            'cancel_url':
                                                                                'https://cancel.com'
                                                                          });
                                                                          debugPrint(
                                                                              'doc added');
                                                                          docRef
                                                                              .snapshots()
                                                                              .listen((ds) {
                                                                            if (ds.exists) {
                                                                              var url = ds.get('url'); //Is there a way to get url using cubit inside a function?
                                                                              if (context.mounted) {
                                                                                Navigator.push(context, MaterialPageRoute(builder: (_) {
                                                                                  return CheckoutPage(url: url);
                                                                                }));

I am getting an uncaught exception breakpoint at docRef.snapshots(). Why does that happen? What is the fix?