ParadoxicalCondition for no reason?

[kkmuffme]

Simplified code snippet https://psalm.dev/r/268b76bdec

No idea why/where it asserts that $unit cannot be "lb"?
=> when I comment the "continue;" the error is gone
=> this is ONLY with "lb". When I put "lbs" or anything else the error is gone too

This error is new in v5 (checked with v4 and it's not there)

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/268b76bdec

<?php
/**
 * @param non-empty-array<string, int> $measurement
 * @param string $target_unit
 *
 * @return float
 */
function convert_scale_measurement_unit( $measurement, $target_unit ) {
	if ( !in_array( $target_unit, array( 'g', 'kg', 'oz', 'lbs', 'lb' ), true ) ) {
		$target_unit = 'g';
	}

	$measured_weight = 0;
	foreach ( $measurement as $unit => $value ) {
		if ( $unit === $target_unit ) {
			$measured_weight += $value;
			continue;
		}

		if ( $unit === 'lb' && $target_unit === 'kg' ) {
			$value *= 0.45359237;
		}

		$measured_weight += $value;
	}

	return round( $measured_weight, 2 );
}

Psalm output (using commit 0af503a):

ERROR: ParadoxicalCondition - 20:8 - Condition (($target_unit is string(kg)) && ($unit is string(lb))) contradicts a previously-established condition ($unit is not string(lb))

[weirdan]

=> this is ONLY with "lb". When I put "lbs" or anything else the error is gone too

Looks like it happens with the value the last element of that array has. If I put lbs last, it starts happening with lbs but emits not issues with lb: https://psalm.dev/r/7ebfb98ceb

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/7ebfb98ceb

<?php
/**
 * @param non-empty-array<string, int> $measurement
 * @param string $target_unit
 *
 * @return float
 */
function convert_scale_measurement_unit($measurement, $target_unit) {
	if (!in_array($target_unit, ['g', 'kg', 'oz', 'lb', 'lbs'], true)) {
		$target_unit = 'g';
	}
    /** @psalm-trace $target_unit */;

	$measured_weight = 0;
	foreach ($measurement as $unit => $value) {
		if ($unit === $target_unit) {
			$measured_weight += $value;
			continue;
		}
        
		if ($unit === 'lbs' && $target_unit === 'kg') {
			$value *= 0.45359237;
		}
        
		$measured_weight += $value;
	}

	return round($measured_weight, 2);
}

Psalm output (using commit 0af503a):

INFO: Trace - 12:37 - $target_unit: 'g'|'kg'|'lb'|'lbs'|'oz'

ERROR: ParadoxicalCondition - 21:7 - Condition (($target_unit is string(kg)) && ($unit is string(lbs))) contradicts a previously-established condition ($unit is not string(lbs))