Harness status: Error

Uncaught TypeError: Cannot read properties of null (reading 'split')

TypeError: Cannot read properties of null (reading 'split')
    at parseKeylist (https://www1.wpt.live/fenced-frame/resources/utils.js:188:18)
    at https://www1.wpt.live/fenced-frame/resources/background-sync-sw-inner.https.html:9:42