Attempting to load captions during the license exchange causes an error.
<track kind="captions" label="English" srclang="en" src="test.vtt" />
It looks like if you programmatically add `TextTrack` on `document.getElementsByTagName('video').addEventListener('firstplay')` the error doesn't occur.
I have verified that this error only occurs when you try and side load captions of encrypted content.
Looking for more information surrounding the problem/capabilities.
Retrieving data ...