Fix implicit nullables #242

Job	Run time
PHP-Linter (8.2) / linter	10s
PHP-Linter (8.4) / linter	13s
PHP-Linter (8.3) / linter	9s
Linter / yaml-linter	4s
Linter / json-linter	28s
PHP-Linter (8.1) / linter	13s
Linter / ecmascript-linter	0s
Linter / style-linter	0s
Unit tests, PHP 8.1, ubuntu-latest	25s
Unit tests, PHP 8.4, ubuntu-latest	17s
Unit tests, PHP 8.1, windows-latest	1m 8s
Unit tests, PHP 8.4, windows-latest	1m 20s
Unit tests, PHP 8.2, windows-latest	1m 10s
Unit tests, PHP 8.3, ubuntu-latest	19s
Unit tests, PHP 8.2, ubuntu-latest	20s
Unit tests, PHP 8.3, windows-latest	1m 14s
Quality control	57s
Security checks	25s
Code coverage	8s
Cleanup artifacts	4s
	9m 4s

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