I have dialog created like this

$('#add_error').click(function(e) {
        $('<div>')
            .load('/someaction/format/html/')
            .dialog({
                title: 'Some title',
                modal: true,
                width: 385,
                close: function() {
                     $(this).remove();
                }
            });

        e.preventDefault();
    });

It works ok, but every third (not really sure if its really third) time I click link to open dialog, it fails with error in firebug

"$("").addClass("ui-widget-overlay") is undefined"

In dialog.js that is piece of code:

var $el = (this.oldInstances.length ? this.oldInstances.splice(0, 1)[0] : $('<div></div>').addClass('ui-widget-overlay'))
                .appendTo(document.body)
                .css({
                    width: this.width(),
                    height: this.height()
                });

under create: function(dialog) method.

Strange thing is that this error does not occur when I remove

close: function() {
                     $(this).remove();
                }

Any idea?