Undefined index: old_sdk

Hi

Thanks for the great plugin, and thank you for the new updates.

I have one issue: I upgraded the plugin a few days ago to 2.3.1, I see and since then I’m seeing the following error the in site’s log file:
PHP Notice: Undefined index: old_sdk in /wp-content/plugins/facebook-comments-plugin/class-frontend.php on line 39

I’m wondering whether there needs to be an isset($options['old_sdk']) check before checking $options['old_sdk'] == 'on', or is there something I must do on the options page?

Thanks again
Lea

https://www.ads-software.com/plugins/facebook-comments-plugin/