Fix TypeError in the segments update code

[sheyll]

No description provided.

[davemevans]

Can you give some background on this? I can't see an associated issue or any way to reproduce?

[sheyll]

I regularly get:
TypeError: lastSegment is undefined

Now looking at the existing code, I got the impression that in the same function, it checks if segments has more than zero elements, but after that it accesses segments[segments.length - 1] without doing that check.

This I think is wrong, hence this PR.

[davemevans]

Can you share a stream?

[sheyll]

Sorry I can't share a stream right now.

Have you read the code? Did I miss something? Because it seems so obvious to me that the code was wrong independent of the exact context - unless it was relying on the TypeError in some way.

[davemevans]

It certainly doesn't look great, but this is the first time this has been reported in code which hasn't changed for some time so it would be interesting to see what is causing the segment list to be empty.

Whilst some check may be necessary, it'd be worth deeper consideration around whether simply doing nothing on empty segment list the correct failure behaviour, and whether it is valid for there to be no segments in this particular scenario. This may well be the right fix, but it'd be worth knowing for sure IMO.

[sheyll]

You are correct in the assesment that this is worth considering deeper.

Anyway, that consideration should not depend on this code remaining broken.

I suggest to create a new issue for that investigatation.

[sheyll]

Why won't you merge what seems like an obvious bug fix?

[dsparacio]

Sorry we are understaffed. Doing the best we can.