Redirect Away if not logged in

functions.php

<?php

function si_redirect_if_not_logged_in() {
	if ( !is_user_logged_in() ) {
		wp_redirect( home_url() );
		exit();
	}
}
add_action( 'pre_si_invoice_view', 'si_redirect_if_not_logged_in' );
add_action( 'pre_si_estimate_view', 'si_redirect_if_not_logged_in' );