docs: PHPStan Codeigniter no type specified

[ddevsr]

Description
See #7731

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

[kenjis]

Ah, PHPStan is correct, but the errors reported.
callExit() will be deprecated in 4.4, so do we remove never for now?

Error: Unreachable statement - code above always terminates.
Error: Unreachable statement - code above always terminates.
Error: Method CodeIgniter\Test\Mock\MockCodeIgniter::callExit() should always throw an exception or terminate script execution but doesn't do that.
 ------ ------------------------------------------------------- 
  Line   system/CodeIgniter.php                                 
 ------ ------------------------------------------------------- 
  368    Unreachable statement - code above always terminates.  
  389    Unreachable statement - code above always terminates.  
 ------ ------------------------------------------------------- 

 ------ --------------------------------------------------------------------- 
  Line   system/Test/Mock/MockCodeIgniter.php                                 
 ------ --------------------------------------------------------------------- 
  22     Method CodeIgniter\Test\Mock\MockCodeIgniter::callExit() should      
         always throw an exception or terminate script execution but doesn't  
         do that.                                                             
 ------ --------------------------------------------------------------------- 

https://github.com/codeigniter4/CodeIgniter4/actions/runs/5886199394/job/15963712417?pr=7830

[paulbalandan]

We can leave it as is in the baseline and remove it once 4.4 is released.

[MGatner]

So does @ddevsr need to rebase and regenerate the baseline?