session_start problem

I have some problem when testing the plugin in debug mode. I’m getting this error:

Notice: session_start(): A session had already been started – ignoring in /wp-content/plugins/super-socializer/super_socializer.php on line 365

Warning: Cannot modify header information – headers already sent by (output started at /wp-content/plugins/super-socializer/super_socializer.php:365) in /home/inorbitsi/dev.inorbit.si/wp-includes/pluggable.php on line 1219

I found a quick solution by checking if $_SESSION is set:

super_socializer.php:365
if(!isset($_SESSION)){
session_start();
}

** using php 7.2 and wp 4.9.8