Fatal error: Declaration of Vitalybaev\GoogleMerchant\RssElement::xmlSerialize(Sabre\Xml\Writer $writer) must be compatible with Sabre\Xml\XmlSerializable::xmlSerialize(Sabre\Xml\Writer $writer): void

[Division70]

Hello !

I have this error when i try to launch the build of an XML feed, :
Fatal error: Declaration of Vitalybaev\GoogleMerchant\RssElement::xmlSerialize(Sabre\Xml\Writer $writer) must be compatible with Sabre\Xml\XmlSerializable::xmlSerialize(Sabre\Xml\Writer $writer): void

[app/src/Vitalybaev/GoogleMerchant/RssElement.php:28]

Is it a compatibilty problem with the last version of Sabre/Xml (4.0.2) ?

Thanks for your help.

Best.

Christophe