When editing terms, properly display an admin `notice-warning` when `tag_ID` is empty.

Also, avoids two related PHP notices when empty or not set (and thus the global `$tag` is a WP_Error object).

Fixes: #34515.

git-svn-id: https://develop.svn.wordpress.org/trunk@35875 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/edit-tag-form.php

@@ -11,7 +11,10 @@ if ( !defined('ABSPATH') )
 	die('-1');
 
 if ( empty($tag_ID) ) { ?>
-	<div id="message" class="updated notice is-dismissible"><p><strong><?php _e( 'You did not select an item for editing.' ); ?></strong></p></div>
+<div class="wrap">
+	<h1><?php echo $tax->labels->edit_item; ?></h1>
+	<div id="message" class="notice notice-warning"><p><strong><?php _e( 'You did not select an item for editing.' ); ?></strong></p></div>
+</div>
 <?php
 	return;
 }

src/wp-admin/edit-tags.php

@@ -152,6 +152,10 @@ case 'bulk-delete':
 case 'edit':
 	$title = $tax->labels->edit_item;
 
+	if ( ! isset( $_REQUEST['tag_ID'] ) ) {
+		break;
+	}
+
 	$tag_ID = (int) $_REQUEST['tag_ID'];
 
 	$tag = get_term( $tag_ID, $taxonomy, OBJECT, 'edit' );

src/wp-includes/admin-bar.php

@@ -574,7 +574,7 @@ function wp_admin_bar_edit_menu( $wp_admin_bar ) {
 				) );
 			}
 		} elseif ( 'edit-tags' == $current_screen->base
-			&& isset( $tag ) && is_object( $tag )
+			&& isset( $tag ) && is_object( $tag ) && ! is_wp_error( $tag )
 			&& ( $tax = get_taxonomy( $tag->taxonomy ) )
 			&& $tax->public )
 		{