Non-shaka error caught in streaming_engine when loading HLS manifest in the presence of mux.js

[chenein]

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
2.5.5

Can you reproduce the issue with our latest release version?
Yes

Can you reproduce the issue with the latest code from master?
Unknown - I am using the google hosted very

Are you using the demo app or your own custom app?
Custom

If custom app, can you reproduce the issue using our demo app?
N/A - depends on my manifest

What browser and OS are you using?
Safari and Firefox on Mac OS X 10.13.6

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
N/A

What are the manifest and license server URIs?

Manifest:
https://cod.ckcufm.com/cgi-bin/stream-server?broadcast_id=45185&program_id=31&streamtype=hlsmaster

Player as embedded:
https://cod.ckcufm.com/programs/ondemand-player.html?id=31356&token=O}6]sg\2(wUsgXPIcT7%2600%2C6UztHNm\HE`1msAt~b%2Bm'0sJp~u

License server: N/A

What did you do?
Playback of an HLS playlist in the presence of mux.js 5.5.1

What did you expect to happen?
Audio!

What actually happened?
Audio player loaded media but failed to start playing, with errors in the console that I was not able to figure out even in debug mode (see image). The error appears to be a non-Shaka error that Shaka is not happy to catch at this point in the code.

Note that if I remove the mux.js library from the head element, then as expected Shaka generates error code 4032 for this HLS stream. I am not an expert in deploying js projects, so it is possible that I have got something wrong with my mux.js build. However, I can't tell what this is because Shaka is eating the error.

[joeyparrish]

Thank you for the report! We will try to reproduce the issue with the manifest URL you included.

[TheModMaker]

It looks like the check for captions isn't valid and we try to append embedded captions for the stream. Since there isn't any video stream, we can't find its timestampOffset. This is the culprit line, caused by the if statement checking for truthy values instead of checking for a non-empty list.