refactor: Fix phpstan codeigniter.modelArgumentInstanceOf

[neznaika0]

Description
I need help.
I still don't understand how to work with generics. I can add simple hints, but any condition raises questions.

How do I specify here "If $which is class-string<Model> ? class-string<Model> : Model|object|string|null" and then update the hint for model($this->modelName)

The phpstan documentation is small. There is no description of most use cases. Did I miss something?

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[paulbalandan]

Maybe this would help: https://phpstan.org/blog/generics-by-examples#function-accepts-any-string%2C-but-returns-object-of-the-same-type-if-it%E2%80%99s-a-class-string

[neznaika0]

RESTFul uses model() internally, so I think it's acceptable to add a Model layer to it.

[samsonasik]

why this change, any test for it ?

[neznaika0]

$this->modelName is always a string. Why is there null there? model() will throw an error if you pass null.
What test do you need? You even need to change the type $this->modelName

[neznaika0]

We didn't agree, I'll just give it back.