BuddyPress.org

Hello,
When i do any ajax requests on my site, i get an error in the debug log:

[22-Aug-2018 11:53:33 UTC] PHP Fatal error: Using $this when not in object context in /home/cliniima/public_html/intranetnova/wp-content/plugins/buddypress/bp-templates/bp-nouveau/buddypress-functions.php on line 99

Where has this code:

if ( function_exists( 'tests_add_filter' ) ) {
	require $this->includes_dir . 'ajax.php';

// Load AJAX code only on AJAX requests.
} else {
	add_action( 'admin_init', function() {
		if ( defined( 'DOING_AJAX' ) && true === DOING_AJAX ) {
			require $this->includes_dir . 'ajax.php'; // Line 99
		}
	}, 0 );
}

And i didn’t do any mods in the core files, just happened to download through WP plugin install page. It prevents ajax from back and front end to work.

Can someone help out? Thanks.