Call to a member function get() on null Error

Thanks for feedback and hints grimpirate, I really appreciate it.
I don't wanto to reinvent the wheel... I'm trying to add a feature ( just a Selection menu in header page) to allow users to switch among the languages in supportedLocales array.
For what I know ( very poor ) Codeigniter has no such features...but any suggestion on this is appreciated.

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I got the issue...
The following code doesn't work anymore, ( weird...it worked fine before Shield installation ):

Code:

if (session_status() == PHP_SESSION_NONE){}