Revert "Keep null value"

[mabdullahsari]

Hi 👋

This PR reverts the changes made in the original PR. Even though I am a proponent of the suggested changes, unfortunately it's a breaking change for people who don't make use of type juggling through the use of declare(strict_types=1).
Moreover, this is also going to break the code of those who are on the most recent PHP versions where str_* functions no longer accept null as a legitimate value.

The suggested changes should be targeted at a v7 or a next branch, ideally.

Thank you 🙏

[freekmurze]

Thank you! I'm going to treat this as a bug fix, and release it under the current major version.

[sdebacker]

Does it mean that a new major version will be created that keeps the null values ?