In the error log files I see many times:

[Mon Oct 22 12:34:20.881302 2018] [error] [pid 15785] mod_proxy_fcgi.c(848): [client xxx.xxx.xxx.xxx:xxxx] AH01071: Got error 'PHP message: PHP Warning: count(): Parameter must be an array or an object that implements Countable in /path/to/site/components/com_jsn/views/list/tmpl/default.php on line 38\nPHP message: PHP Warning: count(): Parameter must be an array or an object that implements Countable in /path/to/site/components/com_jsn/views/list/tmpl/default.php on line 57\n'

Is this a code problem or config problem?
No problems with output. So no hurry.

Kind regards,
Joris