From 9d2a493cea6bbb742db0efc7fac428a519a95aa6 Mon Sep 17 00:00:00 2001
From: Mike Jolley <mike.jolley@me.com>
Date: Wed, 25 Oct 2017 12:51:19 +0100
Subject: [PATCH] Prevent notice on settings page when accessing invalid tab

Closes #17367
---
 .../admin/settings/class-wc-settings-tax.php  |  8 ++++++-
 includes/admin/views/html-admin-settings.php  | 23 +++++++++++++++----
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/includes/admin/settings/class-wc-settings-tax.php b/includes/admin/settings/class-wc-settings-tax.php
index 9dcd44034af..8df905a5bb2 100644
--- a/includes/admin/settings/class-wc-settings-tax.php
+++ b/includes/admin/settings/class-wc-settings-tax.php
@@ -28,7 +28,13 @@ class WC_Settings_Tax extends WC_Settings_Page {
 		$this->id    = 'tax';
 		$this->label = __( 'Tax', 'woocommerce' );
 
-		parent::__construct();
+		add_filter( 'woocommerce_settings_tabs_array', array( $this, 'add_settings_page' ), 20 );
+
+		if ( wc_tax_enabled() ) {
+			add_action( 'woocommerce_sections_' . $this->id, array( $this, 'output_sections' ) );
+			add_action( 'woocommerce_settings_' . $this->id, array( $this, 'output' ) );
+			add_action( 'woocommerce_settings_save_' . $this->id, array( $this, 'save' ) );
+		}
 	}
 
 	/**
diff --git a/includes/admin/views/html-admin-settings.php b/includes/admin/views/html-admin-settings.php
index a4244710bc5..fb1f126eae5 100644
--- a/includes/admin/views/html-admin-settings.php
+++ b/includes/admin/views/html-admin-settings.php
@@ -1,23 +1,36 @@
 <?php
 /**
  * Admin View: Settings
+ *
+ * @package WooCommerce
  */
+
 if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }
 
+$tab_exists        = isset( $tabs[ $current_tab ] ) || has_action( 'woocommerce_sections_' . $current_tab ) || has_action( 'woocommerce_settings_' . $current_tab ) || has_action( 'woocommerce_settings_tabs_' . $current_tab );
+$current_tab_label = isset( $tabs[ $current_tab ] ) ? $tabs[ $current_tab ] : '';
+
+if ( ! $tab_exists ) {
+	wp_safe_redirect( admin_url( 'admin.php?page=wc-settings' ) );
+	exit;
+}
 ?>
 <div class="wrap woocommerce">
 	<form method="<?php echo esc_attr( apply_filters( 'woocommerce_settings_form_method_tab_' . $current_tab, 'post' ) ); ?>" id="mainform" action="" enctype="multipart/form-data">
 		<nav class="nav-tab-wrapper woo-nav-tab-wrapper">
 			<?php
-				foreach ( $tabs as $name => $label ) {
-					echo '<a href="' . admin_url( 'admin.php?page=wc-settings&tab=' . $name ) . '" class="nav-tab ' . ( $current_tab == $name ? 'nav-tab-active' : '' ) . '">' . $label . '</a>';
-				}
-				do_action( 'woocommerce_settings_tabs' );
+
+			foreach ( $tabs as $slug => $label ) {
+				echo '<a href="' . esc_html( admin_url( 'admin.php?page=wc-settings&tab=' . esc_attr( $slug ) ) ) . '" class="nav-tab ' . ( $current_tab === $slug ? 'nav-tab-active' : '' ) . '">' . esc_html( $label ) . '</a>';
+			}
+
+			do_action( 'woocommerce_settings_tabs' );
+
 			?>
 		</nav>
-		<h1 class="screen-reader-text"><?php echo esc_html( $tabs[ $current_tab ] ); ?></h1>
+		<h1 class="screen-reader-text"><?php echo esc_html( $current_tab_label ); ?></h1>
 		<?php
 			do_action( 'woocommerce_sections_' . $current_tab );