False Positive: string|null inferred although null check is in place

[tlamy]

Bug report

phpstan falsely reports string|null type although proper null check is done in ternary.

Code snippet that reproduces the problem

https://phpstan.org/r/3962507d-a02a-447b-9b46-23e08110b40b

<?php declare(strict_types = 1);

function createFromString(string $timespec): DateTime {
	try {
		return new DateTime($timespec, new DateTimeZone('UTC'));
	} catch (Exception) {
		throw new InvalidArgumentException(sprintf('Invalid timespec "%s"', $timespec));
	}
}

$rows = [
	['timespec'=>null],
	['timespec'=>'2020-01-01T01:02:03+08:00'],
];

$result = [];
foreach($rows as $row) {
	$result[] = ($row['timespec'] ?? null) !== null ? createFromString($row['timespec']) : null;
}

Expected output

No error.

Acutal output

Parameter #1 $timespec of function createFromString expects string, string|null given

Did PHPStan help you today? Did it make you happy in any way?

Phpstan helps me every day, and the speed in which issues are fixed is absolutely amazing!

[ondrejmirtes]

Thank you for your kind words! 😊

/cc @rvanvelzen This looks like something that should have been fixed by your recent PR but wasn't.

[github-actions]

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