Tutorial for creating news item doesn't work

Hi, I am going by this tutorial: https://codeigniter.com/user_guide/tutor...items.html.
I believe it is the controller code that is at fault. The main error message says: 
ErrorException

number_format(): Passing null to parameter #1 ($num) of type float is deprecated.

The rest of the error message is the usual gibberish. It may just as well be written in Japanese.
So, it there an updated tutorial? Could someone point toward the solution?

EDIT: This has to be a new one for me. It works on siteground (which is no doubt php 7.x)! So the issue is, that CI4 news tutorial does not work on php 8.

EDIT 2: oh for crying out loud I cannot even respond. This is not exactly making this very easy...