Issue with Session

Hi everyone,

I'm new with CI (4.1.9) and my first steps went well.

But now I'm facing some issue with the session helper.

1.)
I added the following code in my BaseControllers InitController method.

PHP Code:

$this->session = \Config\Services::session(); 


When I use it with $this->session->get() in my controller everything works fine. But I get a

Code:

Call to a member function get() on null

as soon as I use it in one of my models.
How can I use the session service within my models?

2.) In case I check the existence of a session variable I get always a true, even if the variable is not existing.

PHP Code:

$this->session->has('test'); 


Now I'm checking, if this session is null.
Why is the return value of the code above always true?

Thanks in advance.

Could someone support me?