fix(runtime-vapor): correctly check slot existence in ownKeys

[Sdju]

Description

Fixes a bug in the ownKeys trap of the slots proxy where accessing slot.name would throw an error when a dynamic slot returns undefined (e.g., when using v-if with a false condition).

Reproduction: playground

Problem

When using dynamic slots with conditional rendering (via v-if), the ownKeys trap in dynamicSlotsProxyHandlers would attempt to access slot.name without first checking if slot is undefined. This caused a TypeError: Cannot read properties of undefined (reading 'name') when calling Object.keys(slots) or Reflect.ownKeys(slots) on a component instance with conditionally rendered slots.

Solution

Added a null check before accessing slot.name in the ownKeys trap handler. This ensures that when a dynamic slot source function returns undefined, it is properly skipped rather than causing an error.

Testing

• Added a test case slots proxy ownKeys trap correctly reflects dynamic slot presence that verifies Reflect.ownKeys(instance.slots) correctly reflects the presence/absence of dynamic slots when toggled with v-if

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✨ Finishing touches

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[Sdju]

Additional Notes

I also checked for a similar issue in getKeysFromRawProps and resolveDynamicProps (used by useAttrs). While the same pattern exists where resolveFunctionSource can return undefined, the use of for...in loops safely handles null/undefined values without throwing errors (the loop body simply doesn't execute).

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
compiler-dom.global.prod.js	85.5 kB	30 kB	26.5 kB
runtime-dom.global.prod.js	108 kB	40.7 kB	36.6 kB
vue.global.prod.js	167 kB	60.7 kB	54.1 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	48.3 kB	18.9 kB	17.3 kB
createApp	57.3 kB	22 kB	20.1 kB
createApp + vaporInteropPlugin	85.4 kB (+5 B)	31.9 kB (+1 B)	28.8 kB (-40 B)
createVaporApp	27.7 kB (+5 B)	10.6 kB (+1 B)	9.74 kB (-4 B)
createSSRApp	61.6 kB	23.9 kB	21.7 kB
defineCustomElement	63.3 kB	23.9 kB	21.8 kB
overall	72.1 kB	27.3 kB	24.9 kB

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commit: 225cbd7