错误消息指出电子邮件地址是必需的，表明电子邮件是用户池上的必需属性。您已经通过包括电子邮件范围来完成了正确的事情，但是您还必须通过将Facebook电子邮件映射到Cognito电子邮件属性，在Amazon Cognito控制台中包括提供商（在您的情况下为Facebook）的属性映射。请试一下，让我们知道它是否有效。

The error message says that the email address is required which indicates that email is a required attribute on your user pool. You have done the correct thing by including the "email" scope but you also have to include the attribute mapping for the provider (Facebook in your case) in the Amazon Cognito console by mapping facebook email to Cognito email attribute. Please give this a shot and let us know if it worked or not.