Only pass the current screen to the list table constructor when we have a screen to work with. This is not the case for admin-ajax requests. fixes #22570.

git-svn-id: http://core.svn.wordpress.org/trunk@22838 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/list-table.php

@@ -43,8 +43,10 @@ function _get_list_table( $class, $args = array() ) {
 
 		if ( isset( $args['screen'] ) )
 			$args['screen'] = convert_to_screen( $args['screen'] );
-		else
+		elseif ( isset( $GLOBALS['hook_suffix'] ) )
 			$args['screen'] = get_current_screen();
+		else
+			$args['screen'] = null;
 
 		return new $class( $args );
 	}