For an unknown reason I've got null as upload_link from Vimeo a few times.

This breaks the code here:

Vimeo\Upload\TusClientFactory::getTusClient(): Argument #2 ($url) must be of type string, null given, called in /var/task/vendor/vimeo/vimeo-api/src/Vimeo/Vimeo.php on line 599

We should solve it by either throw an exception, allow null or cast to string. I have too little knowledge in this process to know what's best but I can sure open a PR if someone decides which way to go.