[SiteGuard] Fatal error: Function name must be a string: $esc_html

SiteGuard WP Plugin 1.3.1 において、メール送信に失敗して siteguard_error_log へログを書き出す際に下記のエラーが発生して画面が真っ白になります。

Fatal error: Function name must be a string in /…/wp-content/plugins/siteguard/classes/siteguard-login-alert.php on line 51

SiteGuard WP Plugin 1.2.x ではこの問題は起きません。
esc_html が $esc_html となっているのが原因かと思います。下記の修正を行うとエラーになりません。

--- siteguard.default/classes/siteguard-login-alert.php 2016-08-16 11:57:58.000000000 +0900
+++ siteguard/classes/siteguard-login-alert.php 2016-09-13 15:11:28.071760525 +0900
@@ -48,7 +48,7 @@
                $body    = $this->replace_valuable( $body, $username );

                if ( true !== @wp_mail( $user_email, esc_html( $subject ), esc_html( $body ) ) ) {
-                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . $esc_html( $subject ) );
+                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . esc_html( $subject ) );
                }

                return;
diff -urN siteguard.default/classes/siteguard-rename-login.php siteguard/classes/siteguard-rename-login.php
--- siteguard.default/classes/siteguard-rename-login.php        2016-08-16 11:57:58.000000000 +0900
+++ siteguard/classes/siteguard-rename-login.php        2016-09-13 15:08:48.384761568 +0900
@@ -161,7 +161,7 @@
                if ( ! empty( $user_query->results ) ) {
                        foreach ( $user_query->results as $user ) {
                                if ( true !== @wp_mail( $user->get( 'user_email' ), $subject, $body ) ) {
-                                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . $esc_html( $subject ) );
+                                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . esc_html( $subject ) );
                                }
                        }
                }
diff -urN siteguard.default/classes/siteguard-updates-notify.php siteguard/classes/siteguard-updates-notify.php
--- siteguard.default/classes/siteguard-updates-notify.php      2016-08-16 11:57:58.000000000 +0900
+++ siteguard/classes/siteguard-updates-notify.php      2016-09-13 15:08:40.929761464 +0900
@@ -242,7 +242,7 @@
                if ( is_array( $user_query->results ) ) {
                        foreach ( $user_query->results as $user ) {
                                if ( true !== @wp_mail( $user->get( 'user_email' ), $subject, $message ) ) {;
-                                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . $esc_html( $subject ) );
+                                       siteguard_error_log( 'Failed send mail. To:' . $user_email . ' Subject:' . esc_html( $subject ) );
                                }
                        }
                }

jp-secure さん、修正をお願いします！