[php-src] Issue #20194: Using null as an array offset is not deprecated

Issue: https://github.com/php/php-src/issues/20194 Author: thomas-0816 ### Description The following code: ```php <?php $a = [null => 1]; echo $a[null]; ``` Resulted in this output: ``` Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/test.php on line 5 1 ``` But I expected this output instead: ``` Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/test.php on line 3 Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/test.php on line 5 1 ``` ### PHP Version ```plain PHP 8.5.0RC2 (cli) (built: Oct 9 2025 23:32:25) (NTS) Copyright (c) The PHP Group Built by https://github.com/docker-library/php Zend Engine v4.5.0RC2, Copyright (c) Zend Technologies with Zend OPcache v8.5.0RC2, Copyright (c), by Zend Technologies ``` ### Operating System Docker php:8.5.0RC2-cli-bookworm