Invalid unused variable when variable is a reference in an array.

[jpresutti]

Edit: using psalm.phar 4.7
ERROR: UnusedVariable - Router/Router.php:491:13 - $val is never referenced or the value is not used (see https://psalm.dev/077)

 /** @var string $val */
foreach ($arguments as &$val) {
    $val = urlencode($val);
}
return implode('/', $arguments);

[jpresutti]

To be clear, this variable is used when the return of $arguments happens. This is not a valid unused variable.