Prevent RangeError exception when parsing incomplete PES

[robwalch]

This PR will...

Prevent RangeError exception when parsing incomplete PES.

Why is this Pull Request needed?

Remove exceptions in the critical path.

Are there any points in the code the reviewer needs to double check?

I'm not sure if the issue is that the PES are incomplete, empty or simply mishandled further up in the TS demuxer. Merging #2109 would avoid the exception with the test stream in #2415 altogether. That fix is scheduled for the next patch so that we can test the full scope of those changes.

Resolves issues:

Fixes #2415
Relates to #2109

Checklist

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• API or design changes are documented in API.md

[michaelcunningham19]

This is fine by me, however could we simply modify the pre-existing safety checks that exist on lines 439-440?
What you have here now may cover other cases that I'm not considering, but I thought I would ask 😄

The safety check I'm referencing:

    // safety check
    if (!stream || stream.size === 0) {
      return null;
    }	

[robwalch]

@michaelcunningham19 I'd like to, but I'm not certain what the length of payloadStartOffset will be at this point.

hls.js/src/demux/tsdemuxer.js

Line 500 in ffe1569

payloadStartOffset = pesHdrLen + 9;

I think we could change the safety check to || stream.size < 10) { but that still wont cover cases where pesHdrLen ends up topping the input size.