When I create a new condition and apply it to the advertisement, then the site throws error 500. In server logs I see the fatal error:
Method IPS\core\Advertisement::__toString() must not throw an exception, caught ParseError: syntax error, unexpected ':'
File: /htdocs/init.php(867) : eval()'d code
When condition is "unapplied" then error disappears.
The condition is
{{if in_array(request.app, array('forums', 'gallery')}}1{{endif}}