Stop users from logging in if they are not validated (PMPro Email Confirmation)

stop_users_from_logging_in_pmpro.php

<?php

/**
 * This function will stop any user's that aren't validated from logging into your WordPress website.
 * This requires PMPro Email Confirmation - https://www.paidmembershipspro.com/add-ons/email-confirmation-add-on/
 * Add this code to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 * Visit https://paidmembershipspro.com for further assistance.
 */
 
function my_pmpro_check_login( $user, $password ) {

	$validated = get_user_meta( $user->ID, "pmpro_email_confirmation_key", true );

	if( $validated != 'validated' && !empty( $validated ) ) {
		return new WP_Error( 'user_not_verified', 'User has not validated their email' ); 
	}

	return $user;
}

add_filter( 'wp_authenticate_user', 'my_pmpro_check_login', 10, 2 );

This was forked from a previous gist that's more up-to-date with the latest standards. See full article - https://www.paidmembershipspro.com/restrict-user-login-for-members-only/