From e164ec2461b36e5ffd017433531e23d01cfc9b8e Mon Sep 17 00:00:00 2001
From: Andrew Nacin <nacin@git.wordpress.org>
Date: Sun, 13 Apr 2014 16:40:07 +0000
Subject: [PATCH] Customizer: Account for a sidebar with no container to which
 classes can be added.

props ocean90.
fixes #27780.


git-svn-id: https://develop.svn.wordpress.org/trunk@28100 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/js/customize-preview-widgets.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/js/customize-preview-widgets.js b/src/wp-includes/js/customize-preview-widgets.js
index 6bd7e02464..cccc5962f8 100644
--- a/src/wp-includes/js/customize-preview-widgets.js
+++ b/src/wp-includes/js/customize-preview-widgets.js
@@ -50,7 +50,14 @@
 
 				emptyWidget = $(widgetTpl);
 				widgetSelector = emptyWidget.prop('tagName');
-				widgetClasses = emptyWidget.prop('className').replace(/^\s+|\s+$/g, '');
+				widgetClasses = emptyWidget.prop('className');
+
+				// Prevent a rare case when before_widget, before_title, after_title and after_widget is empty.
+				if ( ! widgetClasses ) {
+					return;
+				}
+
+				widgetClasses = widgetClasses.replace(/^\s+|\s+$/g, '');
 
 				if ( widgetClasses ) {
 					widgetSelector += '.' + widgetClasses.split(/\s+/).join('.');