Future<void> signInWithEmailAndPassword(String email, String password) async {
  try {
    await firebaseAuth.signInWithEmailAndPassword(email: email, password: password);
    final credential = EmailAuthProvider.credential(email: email, password: password);
    await FirebaseAuth.instance.currentUser?.linkWithCredential(credential);
  } on FirebaseAuthException catch (e) {
    throw FirebaseAuthException(code: e.code, message: e.message);
  }
}