Exception: Cannot read property 'text' of undefined in !thumbnail.frames[0].text.startsWith('/')

[laukstein]

trafficstars

Fails in src/js/plugins/preview-thumbnails.js:156:41 when correctly used .vtt, exception noticed on Linux Chrome v65.0.3325.

if (
  | !thumbnail.frames[0].text.startsWith('/') &&
  | !thumbnail.frames[0].text.startsWith('http://') &&
  | !thumbnail.frames[0].text.startsWith('https://')
  | ) {

[duncanmcclean]

Did you figure this one out? I'm running into this now.