refactor: Improving typings #50

Job	Run time
phpstan / PHPStan	18s
phpunit / PHPUnit (8.4, 6.4.*, highest, max[direct]=0)	16s
phpunit / PHPUnit (8.4, 6.4.*, lowest, disabled=1)	16s
sonarcloud / sonarcloud	44s
	1m 34s

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