Fix implicit nullables #239

Job	Run time
PHP-Linter (8.3) / linter	13s
PHP-Linter (8.4) / linter	13s
PHP-Linter (8.1) / linter	11s
Linter / json-linter	25s
PHP-Linter (8.2) / linter	11s
Linter / yaml-linter	5s
Linter / style-linter	0s
Linter / ecmascript-linter	0s
Unit tests, PHP 8.1, windows-latest	1m 18s
Unit tests, PHP 8.4, windows-latest	1m 5s
Unit tests, PHP 8.2, windows-latest	1m 10s
Unit tests, PHP 8.1, ubuntu-latest	25s
Unit tests, PHP 8.2, ubuntu-latest	16s
Unit tests, PHP 8.3, windows-latest	1m 2s
Unit tests, PHP 8.4, ubuntu-latest	19s
Unit tests, PHP 8.3, ubuntu-latest	19s
Quality control	0s
Security checks	0s
Code coverage	0s
Cleanup artifacts	0s
	7m 12s

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