Warning from archive-jetpack-portfolio.php

I am a great fan of shapley but discovered a problem when using the portfolio with project types. I have added two different project types in the portfolio and everything is fine if I do not use one of them. But using one project types I get a warning implode: invalid argument passed in domain.com/wp-content/themes/shapely-child/archive-jetpack-portfolio.php in line 46. Anyone who can help me?
Thanks, Axel