Calling z-push-admin/z-push-top from the kopano backend dir results in php traceback

root@webapp:/usr/share/z-push/backend/kopano# z-push-admin -a list
PHP Notice:  Use of undefined constant LOGBACKEND_CLASS - assumed 'LOGBACKEND_CLASS' in /usr/share/z-push/lib/core/zlog.php on line 141
PHP Stack trace:
PHP   1. {main}() /usr/share/z-push/z-push-admin.php:0
PHP   2. ZPush::CheckConfig() /usr/share/z-push/z-push-admin.php:44
PHP   3. ZPushException->__construct() /usr/share/z-push/lib/core/zpush.php:195
PHP   4. ZLog::Write() /usr/share/z-push/lib/exceptions/zpushexception.php:41
PHP   5. ZLog::getLogger() /usr/share/z-push/lib/core/zlog.php:83
PHP   6. zpush_error_handler() /usr/share/z-push/lib/core/zlog.php:141
PHP   7. ZLog::Write() /usr/share/z-push/lib/core/zlog.php:189
PHP   8. ZLog::getLogger() /usr/share/z-push/lib/core/zlog.php:83
The configured logging class `LOGBACKEND_CLASS` does not exist. Check your configuration.
The configured logging class `LOGBACKEND_CLASS` does not exist. Check your configuration.
FatalMisconfigurationException: The BASE_PATH is not configured. Check if the config.php file is in place.