PHP Notice When Adding Widget to Sidebar

Hi, we’re using Restrict Widgets 1.3.1 on WordPress 4.9.5. During some unrelated testing I noticed a PHP notice being logged for the plugin. It appears to happen when a widget is first added to a sidebar and saved without setting any widget restrictions.

PHP Notice: Undefined index: widget_multiselect in [path redacted]/wp-content/plugins/restrict-widgets/restrict-widgets.php on line 1273

Looks like it just needs an isset() check added to the if statement.

Thanks for your work on this plugin. We really appreciate it.