If Empty Option?

I am reading information about courses from this link http://aixtra.klinikum.rwth-aachen.de/rest_index.php and usualy there is the code=”0″ and in data=[] are the courses in an array.
Sometimes there are no courses and if so I get code=”1″ and message=”Some text”
How can I configure my webpage to read message instead if data is empty?
Is there something like [jsoncontentimporter url=”http://aixtra.klinikum.rwth-aachen.de/rest_index.php” basenode=”data:IfEmpty:message”]…[/jsoncontentimporter]

https://ww.wp.xz.cn/plugins/json-content-importer/