callable.js

final HttpsCallable callable =
                                  CloudFunctions.instance.getHttpsCallable(
                                functionName: 'registerUser',
                              );

                              try {
                                await callable.call(<String, dynamic>{
                                  'email': email.text,
                                  'displayName': name.text,
                                  'password': password.text
                                });

                                await FirebaseAuth.instance
                                    .signInWithEmailAndPassword(
                                        email: email.text, password: password.text);
                                Navigator.pushReplacement(
                                  context,
                                  MaterialPageRoute(
                                      builder: (context) => AuthCheck()),
                                );
                              } catch (e) {
                                setState(() {
                                  loading = false;
                                });
                                print(e);
                              }