KeepAlive does not work with a child whose key = NaN

[danyadev]

Version

3.0.0-beta.18

Reproduction link

https://jsfiddle.net/danyadev/d73m9qek/

Steps to reproduce

Click on the button and look at the console

What is expected?

no errors

What is actually happening?

TypeError: parentComponent.ctx.deactivate is not a function
    at unmount (vue.global.js:8623)
    at patch (vue.global.js:7711)
    at Object.sharedContext.activate (vue.global.js:9216)
    at processComponent (vue.global.js:8081)
    at patch (vue.global.js:7742)
    at componentEffect (vue.global.js:8268)
    at Object.reactiveEffect [as update] (vue.global.js:4181)
    at updateComponent (vue.global.js:8157)
    at processComponent (vue.global.js:8088)
    at patch (vue.global.js:7742)

---

If the Foo component is added with a deactivated hook, then it will work on the first click, but the error will not disappear

[yyx990803]

NaN === NaN // false

Make sure to never use NaN as a key.

[danyadev]

I understand that this is a bad use case for key. Nevertheless, it was used in my code, although I did not even know about it, and everything worked perfectly.

[yyx990803]

This is a wontfix - key by definition must be identity unique and NaN is not a valid key. I added a warning for it in da40ff49.