Bug: as per React: unmount callbacks should be called before removing DOM

[Havunen]

unmount callbacks should be called before removing DOM.
See https://jsfiddle.net/Luotcj1f/ for React behavior.
at least this line in wrong:
https://github.com/NervJS/nerv/blob/master/packages/nerv/src/vdom/patch.ts#L95-L96

Didn't check any other places.

[yuche]

See https://codesandbox.io/s/j2wym3n6w5 for Nerv behavior.
I guess Nerv can still access to the dom on componentWillUnmount function.

But still, there is bug in Top level API render, Nerv can just return null when first argument is null.
Thanks for point that out.

[Havunen]

My point was that when doing keyed algo you remove DOM first, then call the callbacks. Ok I create full reproduce wait a sec.

[Havunen]

https://codesandbox.io/s/3x29y3040m
edit: there is something else too ... I create another fiddle

another where it fails: https://codesandbox.io/s/5xpp5q4lyn

[yuche]

Thanks for the reproduce. It's a really nice that you can help us on the weekend. ❤️

[yuche]

There is serval tests for this issue.