I have this json content, and it causes a very strange output from demo viewer.
{
"@context": "http://purl.imsglobal.org/ctx/caliper/v1/Context",
"@type": "http://purl.imsglobal.org/caliper/v1/AssessmentEvent",
"action": "http://purl.imsglobal.org/vocab/caliper/v1/action#Started"
}
Ironically, this issue is not present in the current json.human.js project