Added explicit nullable types to satisfy PHP 8.4 deprecation

[akinspe]

This PR fixes a variety of deprecation warnings found when running in PHP 8.4.

In particular it fixes "Implicitly nullable parameter types are now deprecated." by explicitly declaring nullable parameters.

[tvdijen]

Thanks! But I'm not sure we want to merge this. It's a change of signatures and we're already working on a complete rewrite in a new major version..

[akinspe]

That's fair. Technically the signatures aren't different as PHP handles the type $param= null implicitly as a nullable type ?type $param=null . It just means that people will see MANY deprecation warnings in PHP 8.4. Given you had started to support 8.4 in a previous commit I thought you would want to fix this. Here's some more info:

https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullable-deprecated

Thanks for your consideration.

[tvdijen]

Oh, since it appears to be completely backwards compatible, I have no problem merging this!
I'll await the tagged second pair of eyes to be on the safe side!

[tvdijen]

Actually, the unit tests speak for themselves.. I'll tag a new release