Undefined index: HTTP_USER_AGENT in views_lazy_load_plugin_display_extender->isExcludedUserAgent()

Dear Team,

I'm getting following message logged under Recent log messages section Home » Administration » Reports

Notice: Undefined index: HTTP_USER_AGENT in views_lazy_load_plugin_display_extender->isExcludedUserAgent() (line 52 of /var/www/dailynews.lk/public_html/sites/all/modules/views_lazy_load/includes/views/views_lazy_load_plugin_display_extender.inc).

Thank you