我的自定义post metabox出现此错误。自定义post和metabox工作正常，但如果我已启用调试，并且在尝试保存任何其他页面或post时，我将收到一个错误：

注意：未定义的索引：在/Users/jay/site/wp-content/themes/mytheme/dogs-post-type中。php在线53

注意：未定义的索引：在/Users/jay/site/wp-content/themes/mytheme/dogs-post-type中。php在线53

警告：无法修改标题信息-标题已由/Users/jay/site/wp-content/themes/mytheme/dogs-post-type.php:53）中的/Users/jay/site/wp-includes/pluggable发送。php在线876

我的代码：

 <?php

      // Add new custom post for dogs
      function example_dogs_custom_init() {
          $args = array( 
            \'label\' => \'Dogs\',
            \'public\' => true,
            \'capability_type\' => \'post\',
            \'hierarchical\' => true,
            \'has_archive\' => true,
            \'menu_position\' => 5,
            \'supports\' => array(\'title\', \'editor\'),
            \'rewrite\' => array(\'slug\' => \'pets/dogs\', \'with_front\' => false)
          );
          register_post_type( \'dogs\', $args );
      }
      add_action( \'init\', \'example_dogs_custom_init\' );


      // METABOX breed
      add_action("add_meta_boxes", \'test_add_post_meta_boxes_breed\');

      function test_add_post_meta_boxes_breed() {
        add_meta_box(
        \'breed-meta\',      // Unique ID
        \'Breed\',   // Title
        \'breed_cb\',   // Callback function
        \'dogs\',         // Admin page (or post type)
        \'side\',         // Context
        \'default\'         // Priority
        );
      }

      function breed_cb() {
        global $post;
        $breed_input = get_post_meta($post->ID, \'breed_field\', true);

        // unique identifier, name of hidden field
        wp_nonce_field(__FILE__, \'at_nonce\');
        ?>
        <label for="breed_field">Breed:</label>
        <input type="text" name="breed_field" id="breed_field" value="<?php echo $breed_input; ?>" />
        <br><span></span><?php
      }

      add_action(\'save_post\', function() {
        global $post;
        if ( defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE ) return;
        // security check - nonce

        // verify this came from the our screen and with proper authorizarion,
        // because save_post can be triggered at other times
        if ( $_POST && !wp_verify_nonce($_POST[\'at_nonce\'], __FILE__) ) {
            return;
        }

        if ( isset($_POST[\'breed_field\']) ) {
              update_post_meta($post->ID, \'breed_field\', $_POST[\'breed_field\']);
        }

      });

    ?>