Upgrade from PHP71 to PHP72 breaks icingaweb2

[Xavier Humbert]

Context FreeBSD 11-STABLE, last pkg upgrade led to update PHP71 to 
PHP72.
php72-json is installed, but when I launch a navigator, IcingaWeb2
crashes with :

> Call to undefined function Icinga\Util\json_encode() in
> /usr/local/www/icingaweb2/library/Icinga/Util/Json.php:57
> 

Any idea ?

Thanks

-- 
Xavier