Sends /page/ paths with a negative category parameter to base uri

theme-functions.php

/**
 * Sends /page/ paths with a negative category parameter to base uri
 */
function csm_no_negative_cat_list() {

	if ( isset( $_GET['cat'] ) && $_GET['cat'] == -1  ) {

		$uri = 'https://' . $_SERVER['HTTP_HOST'] . $_SERVER["REQUEST_URI"];
		$parsed_uri = parse_url( $uri );
		$parsed_path = preg_replace( "/\/page\/[0-9]+/", '', $parsed_uri['path'] );
		$redirect = 'https://' . $parsed_uri['host'] . $parsed_path;
		wp_redirect( $redirect, 301 );

		exit;
	}

} add_action( 'pre_get_posts', 'csm_no_negative_cat_list' );