Customizer: Remove a throw error call which prevents further actions, like jqxhr.always().

props westonruter.
fixes #31501.
Built from https://develop.svn.wordpress.org/trunk@31816


git-svn-id: http://core.svn.wordpress.org/trunk@31798 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-widgets.js

@@ -1852,12 +1852,7 @@
 			controlContainer.slideDown( function() {
 				if ( isExistingWidget ) {
 					widgetFormControl.updateWidget( {
-						instance: widgetFormControl.setting(),
-						complete: function( error ) {
-							if ( error ) {
-								throw error;
-							}
-						}
+						instance: widgetFormControl.setting()
 					} );
 				}
 			} );