Exception -Array to string conversion- after update

Hello everyone,

first of all I am not the the designer of the site wich our problem is all about, nor do I ever had conections to grav befor.
I’m only the admin of the server and I had to update php along with other stuff for security reasons.
I started with updating php from 7.1 to 7.2 afterwards we updatet grav. Everything went fine- no errors. Site is coming up - all fine. Expecting one thing: clicking in the backend on a content element type modular/modular_tiles the following error comes up:

Can anyone give me a hint on how to fix that problem?

Thanks in advanse.