error log :

PHP Notice:  Trying to get property of non-object in ***\wp-admin\includes\template.php on line 699
PHP Stack trace:
PHP   1. {main}() ***\wp-admin\post-new.php:0
PHP   2. include() ***\wp-admin\post-new.php:85
PHP   3. do_meta_boxes() ***\wp-admin\edit-form-advanced.php:686
PHP   4. call_user_func:{***\wp-admin\includes\template.php:1037}() ***\wp-admin\includes\template.php:1037
PHP   5. Piklist_Meta::meta_box() ***\wp-admin\includes\template.php:1037
PHP   6. Piklist::render() ***\modules\piklist\includes\class-piklist-meta.php:313
PHP   7. include() ***\modules\piklist\includes\class-piklist.php:507
PHP   8. touch_time() ***\modules\piklist\parts\meta-boxes\submitdiv.php:218

my custom post :

 	function register_slider_posttype() {
		$labels = array(
			'name'				=> _x( 'Slider', 'post type general name',  LANG_STRING),
			'singular_name'		=> _x( 'Slider', 'post type singular name', LANG_STRING),
			'add_new'				=> __( 'New Slider', LANG_STRING),
			'add_new_item'		=> __( 'Add New Slider', LANG_STRING ),
			'edit_item'			=> __( 'Edit Slider' , LANG_STRING),
			'new_item'			=> __( 'New Slider', LANG_STRING ),
			'view_item'			=> __( 'View Slider', LANG_STRING ),
			'search_items'			=> __( 'Search Slider', LANG_STRING ),
			'not_found'			=> __( 'Not found Slider', LANG_STRING ),
			'not_found_in_trash'		=> __( 'Not Slider in trash', LANG_STRING ),
			'parent_item_colon'		=> __( 'Slider', LANG_STRING ),
			'menu_name'			=> __( 'Slider', LANG_STRING )
				
		);
		
		$taxonomies = array();
		$slug = 'slider';
		$supports = array('title','thumbnail', 'editor');
		
		$post_type_args = array(
			'labels' 						=> $labels,
			'singular_label' 			=> __('Slider', LANG_STRING),
			'public' 						=> true,
			'show_ui' 					=> true,
			'publicly_queryable'		=> true,
			'query_var'					=> true,
			'capability_type' 			=> 'post',
			'has_archive' 				=> true,
			'hierarchical' 				=> false,
			'_builtin' 					=> false,
			'rewrite' 						=> array('slug' => $slug, 'with_front' => true ),
			'supports' 					=> $supports,
			'menu_icon' 				=> 'dashicons-clipboard',
			'menu_position'		 	=> 30,
			'taxonomies'				=> $taxonomies	
		);
		 
		register_post_type($slug, $post_type_args);
		
	}
	
	add_action('init', 'register_slider_posttype');