Uncaught NullPointer Exception in Karaf console from com.entwinemedia.fn.data.json.SimpleSerializer.toJson

Steps to reproduce:
1. Opencast was running for 5 hours with 7 Videos being processed.
2. Without a know issue NullPointer Exception showed up in the Karaf console.
3. This error does not show up in the logs. And there is no ERROR in the logs that might relate to this NPE

Actual Results:

Expected Results:

Workaround (if any):