Opencart Plugin Error

Hi Team we are running opencart with litespeed enabled on the VPS. Its working fine, but we are getting this error in our logs.

2021-01-02 4:36:19 - PHP Notice: Undefined index: HTTP_USER_AGENT in /home/public_html/catalog/controller/extension/module/lscache.php on line 555

line 555: $comment = '<!-- LiteSpeed Cache created with user_agent: ' . $_SERVER['HTTP_USER_AGENT'] . ' -->' . PHP_EOL;

Is this because our site is HTTPS and not HTTP?