'getCredential' is deprecated and shouldn't be used. Deprecated in favor of `FacebookAuthProvider.credential()`. credentialにする。
PhoneVerificationFailed => FirebaseAuthException
FirebaseAuth.instance.currentUser() => () 不要で await 不要?
'documentID' is deprecated and shouldn't be used. Deprecated in favor of `.id`. Try replacing the use of the deprecated member with the replacement. => idで
'documents' is deprecated and shouldn't be used. Deprecated in favor of `.docs`. Try replacing the use of the deprecated member with the replacement. => docsになった
document.data => document.data() みたいにカッコがないとFunctionになってしまう
'getDocuments' is deprecated and shouldn't be used. Deprecated in favor of `.get()`. Try replacing the use of the deprecated member with the replacement. => get() でOK
'Firestore' is deprecated and shouldn't be used. Class Firestore is deprecated, use 'FirebaseFirestore' instead.. Firestore => FirebaseFirestore