Can't access userAttributes of listUsersRes.Users in AWS lambda function

I'm filtering out unconfirmed emails in lambda function. I jsut want to access email of every user in my listUsersRes.Users. I have tried for listUsersRes.Users[0].Username it is returning username perfectly. But when I'm trying listUsersRes.Users[0].Email or listUsersRes.Users[0].userAttributes.email or listUsersRes.Users[0].request.userAttributes.email it is returning null. I have aslo AttributesToGet: ["email"].But I don't know why it is not working for email.

My Full Function code:

exports.handler = async (event, context, callback) => {
   const cognitoProvider = new aws.CognitoIdentityServiceProvider({apiVersion: "2016-04-18"});
     if (event.triggerSource == "PreSignUp_SignUp" ||event.triggerSource == "PreSignUp_AdminCreateUser" || event.triggerSource=="PreSignUp_ExternalProvider") {
    try {
     
       const listUserParams={UserPoolId: event.userPoolId,AttributesToGet: ["email",],Filter: `cognito:user_status= \"${"UNCONFIRMED"}\"`, Limit: 10 };
       const listUsersRes = await cognitoProvider.listUsers(listUserParams).promise();
       
       if (listUsersRes.Users.length >= 0) {
           return callback(new Error(listUsersRes.Users[0].Username), event);//this line I'm modifying to check email attribute 
} 
          }
    catch (error) {return callback(new Error("catch error"), event);}
   }
else {
    var error = "This provider is not supported";
    callback(new Error(error), event);
 }

};

I think I'm unaware of something. If you know please help.

My permissions:

       "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogStream",
                "logs:PutLogEvents",
                "cognito-idp:AdminInitiateAuth",
                "cognito-idp:ListUsers",
                "cognito-idp:AdminUpdateUserAttributes",
                "cognito-idp:AdminGetUser"
            ],