`sourceIndex` on `Selector` nodes

[romainmenke]

see : #36

I think this was previously also missing, was added and then removed again?
Not entirely sure how to read that change and a lot of time has passed since then.

The TypeScript typings suggest that sourceIndex should exist on all nodes and should never be undefined.

Was there a specific reason why sourceIndex is missing, or should we just add it?

[alexander-akait]

I’ll answer honestly - I don’t remember 😄 Anyway if you found a bug, feel free to send a PR

[romainmenke]

Cool!

I am currently working around it by doing selector.first.sourceIndex but that is a bit flaky and only works if the first node wasn't removed or altered.

I'll send a PR when I find some time 🙇