Allow slot names to be numbers

[posva]

Closes #5480

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• Bugfix
• Feature
• Code style update
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• Yes
• No

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Other information:

[posva]

So flow is complaining about the name value being undefined inside of the if but I don't see how that's possible...
Edit: tried to search for an existing issue in flow but no luck

[yyx990803]

Well let's just make it name: any

[posva]

@yyx990803 That won't change the error, I should have posted it to make it clearer:

src/core/instance/render-helpers/resolve-slots.js:22
 22:       const slot = (slots[name] || (slots[name] = []))
                         ^^^^^^^^^^^ access of computed property/element. Computed property cannot be accessed with
 22:       const slot = (slots[name] || (slots[name] = []))
                               ^^^^ possibly uninitialized variable

[HerringtonDarkholme]

I guess this is caused by flow's wrong flow analysis. name is declared in outer block, not in the name = child.data.slot check expression. In this case, flow might be confused about whether name will be changed.

Changing to this will work

    if ((child.context === context || child.functionalContext === context) &&
        child.data && child.data.slot != null) {
      const name = child.data.slot
}