What happens if RTCDataChannelInit.negotiated is true, but id is absent?

[taylor-b]

This is the inverse of #1413: an application negotiating the data channel out-of-band, but not providing an ID. This is guaranteed to not work, since one side would select an even ID and one side would select an odd ID, and they wouldn't match up. So unless I'm missing something, I think we should throw an error when this is attempted.

[lgrahl]

I think we should throw an error when this is attempted.

👍 for an explicit API.

Again, I believe we should eventually unify negotiated and id unless there's a use case for having them separate (as commented here earlier). Edit (as a note to that comment): We could use a completely new field called negotiatedId and have a transitional period where current behaviour is applied in case negotiated or id is present and new behaviour in case negotiatedId is present.

[stefhak]

@adam-be to provide a PR.

[adam-be]

Patched our current behavior, but I agree that the single attribute API mentioned above is preferable.