Bug report

Having a code:

<?php declare(strict_types = 1);

/**
 * @param  array{0: string, 1?: string} $a
 * @return array{0: string, 1?: string}
 */
function rrr(array $a): array
{
	return array_reverse($a);	
}

it results with an error:

Function rrr() should return array{0: string, 1?: string} but returns array{0?: string, 1: string}.

which is not true, having array of 1 or 2 strings revered, it will always results with an array of 1 or 2 strings.

Code snippet that reproduces the problem

https://phpstan.org/r/13270977-2e74-413f-9d7f-904dd76b9096

Expected output

No issue reported.

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