fix(runtime-core): prevent merging model listener when value is null or undefined

[edison1105]

fix https://github.com/vuejs/ecosystem-ci/actions/runs/23529115737/job/68488818862

Summary by CodeRabbit

• Bug Fixes
  • Fixed model listener property handling in prop merging: null or undefined model listener properties are now correctly omitted from the merged result instead of being preserved.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 0a2a6bf8-605c-4b05-bffb-1dce2396de1b

📥 Commits

Reviewing files that changed from the base of the PR and between 88ed045 and c878a8f.

📒 Files selected for processing (2)

• packages/runtime-core/__tests__/vnode.spec.ts
• packages/runtime-core/src/vnode.ts

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📝 Walkthrough

Walkthrough

The PR modifies mergeProps in the vnode utility to conditionally omit model listener properties (like onUpdate:modelValue) when both incoming and existing values are null, preventing these null entries from persisting in merged props. The test suite is updated with assertions to verify this new behavior.

Changes

Cohort / File(s)	Summary
Model Listener Null Handling packages/runtime-core/src/vnode.ts	Updated mergeProps to skip assigning null model listener properties identified via isModelListener(key), preventing unwanted preservation of onUpdate:modelValue and similar model listeners.
Test Coverage packages/runtime-core/__tests__/vnode.spec.ts	Added assertions verifying that model listener properties set to undefined or null are not retained in merged props, contrasting with regular event handler behavior.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• fix(runtime-core): preserve nullish event handlers in mergeProps #14550: Modifies mergeProps logic for event handlers; this PR implements inverse behavior for model listeners specifically, touching the same conditional assignment logic in the merge operation.

Suggested labels

ready to merge, :hammer: p3-minor-bug

Poem

🐰 A model listener null, now wisely dismissed,
No longer preserved when both values have missed.
Event handlers stay true, but these special ones bend—
Clean props for clean models, our merger's best friend! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: preventing merging of model listeners when their values are null or undefined, which matches the implementation in both the test and source changes.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch edison/fix/mergeProps

---

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commit: c878a8f

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	105 kB (+6 B)	39.8 kB (+8 B)	35.7 kB (-48 B)
vue.global.prod.js	164 kB (+6 B)	59.8 kB (+5 B)	53.2 kB (-33 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	48.3 kB (+6 B)	18.8 kB (+3 B)	17.2 kB (+4 B)
createApp	56.4 kB (+6 B)	21.8 kB (+5 B)	19.9 kB (+12 B)
createSSRApp	60.6 kB (+6 B)	23.6 kB (+5 B)	21.5 kB (+9 B)
defineCustomElement	62.6 kB (+6 B)	23.8 kB	21.6 kB (+5 B)
overall	70.9 kB (+6 B)	27.2 kB (+4 B)	24.8 kB (+69 B)

[edison1105]

/ecosystem-ci run

[vue-bot]

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
quasar	❌ failure	❌ failure
language-tools	❌ failure	❌ failure
vue-i18n	✅ success	✅ success
router	✅ success	✅ success
vuetify	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
vant	✅ success	✅ success
nuxt	✅ success	✅ success
vue-macros	✅ success	✅ success
primevue	✅ success	✅ success
radix-vue	✅ success	✅ success
vue-simple-compiler	✅ success	✅ success
vueuse	✅ success	✅ success
vitepress	✅ success	✅ success
pinia	✅ success	✅ success
test-utils	✅ success	✅ success