[css-view-transitions-2] Revisit the behavior of skipping the view transition when there are duplicate names

[noamr]

Currently duplicate view-transition-name in a view transition is an error condition that skips the entire transition.
While it makes sense to only support one element on each side, perhaps skipping the entire transition on an error condition is too jarring, and simply picking one would be a better user experience in those scenarios?

We could probably pick the first or last matching in document order (presumably last because it's CSS?)

[vmpstr]

We can maybe avoid skipping the transition but make it an console warning or something along the lines so that the developer can discover the fact that there is some ambiguity in their CSS set up.

I'm supportive of this

@nt1m @emilio what do you folks think?

[emilio]

A console warning seems fine... Picking the first one seems a bit easier implementation-wise since you can process as you go, and it matches the way we currently do the check, but I don't have super-strong feelings.

However that brings the question of what to do with other error conditions... Should we just skip e.g. fragmented elements? That kind of silent failure might be worse...

[noamr]

A console warning seems fine... Picking the first one seems a bit easier implementation-wise since you can process as you go, and it matches the way we currently do the check, but I don't have super-strong feelings.

However that brings the question of what to do with other error conditions... Should we just skip e.g. fragmented elements? That kind of silent failure might be worse...

I think this is the kind of error that should be represented in dev-tools (or equivalents), and maybe have an error event or some such if it can help, but try to default to not skipping the transition in either case.