Wordfence is having an issue with the headers-security-advanced-hsts-wp.php in Version 5.2.5.
Modified plugin file: wp-content/plugins/headers-security-advanced-hsts-wp/headers-security-advanced-hsts-wp.php
As a test I downloaded the latest copy of Headers Security Advanced & HSTS WP from the WordPress.org site, extracted and replaced headers-security-advanced-hsts-wp.php, but it still has an issue with it.
The file differences are shown below:
Original
30 function hsts_plugin_get_headers( array $headers = array() ): array {
Modified version
30 function hsts_plugin_get_headers( $headers = array() ) {
31 if ( ! is_array( $headers ) ) {
32 $headers = array();
33 }
