Object of class stdClass could not be converted to string after edition image addon

Hello !

I used Educon Template for my website and each time I would like to edit an image, I've this message of error : Object of class stdClass could not be converted to string

For example : https://www.cctds.fr/terres-de-saone/conseil-communautaire.html

I tried to edit the site.php file (adding is_string or serialize arround $image) and delete it but nothing works.

Thanks in advance for your help !