use Symfony\Component\PropertyInfo\Extractor\ReflectionExtractor;class MyClass{    public function getA(): mixed {}}$reflection = new ReflectionExtractor();$reflection->getTypes(MyClass::class, 'a');

PHP Fatal error:  Uncaught InvalidArgumentException: "mixed" is not a valid PHP type. in /path/to/symfony/src/Symfony/Component/PropertyInfo/Type.php:70