fix(server-renderer): propagate sync errors from ssrRenderSuspense

[danielroe]

resolves nuxt/nuxt#28162

we want errors when rendering to throw - but at the moment a sync throw inside the default slot gets converted by the async-function machinery into a rejected Promise<void> that is then thrown away...

Summary by CodeRabbit

• Bug Fixes

  • Fixed error propagation in server-side rendering with Suspense to ensure synchronous errors are correctly handled and reported during rendering.

• Tests

  • Added test case to verify synchronous error handling in Suspense rendering scenarios.

[pkg-pr-new]

Open in StackBlitz

@vue/compiler-core

pnpm add https://pkg.pr.new/@vue/compiler-core@14804

npm i https://pkg.pr.new/@vue/compiler-core@14804

yarn add https://pkg.pr.new/@vue/compiler-core@14804.tgz

@vue/compiler-dom

pnpm add https://pkg.pr.new/@vue/compiler-dom@14804

npm i https://pkg.pr.new/@vue/compiler-dom@14804

yarn add https://pkg.pr.new/@vue/compiler-dom@14804.tgz

@vue/compiler-sfc

pnpm add https://pkg.pr.new/@vue/compiler-sfc@14804

npm i https://pkg.pr.new/@vue/compiler-sfc@14804

yarn add https://pkg.pr.new/@vue/compiler-sfc@14804.tgz

@vue/compiler-ssr

pnpm add https://pkg.pr.new/@vue/compiler-ssr@14804

npm i https://pkg.pr.new/@vue/compiler-ssr@14804

yarn add https://pkg.pr.new/@vue/compiler-ssr@14804.tgz

@vue/reactivity

pnpm add https://pkg.pr.new/@vue/reactivity@14804

npm i https://pkg.pr.new/@vue/reactivity@14804

yarn add https://pkg.pr.new/@vue/reactivity@14804.tgz

@vue/runtime-core

pnpm add https://pkg.pr.new/@vue/runtime-core@14804

npm i https://pkg.pr.new/@vue/runtime-core@14804

yarn add https://pkg.pr.new/@vue/runtime-core@14804.tgz

@vue/runtime-dom

pnpm add https://pkg.pr.new/@vue/runtime-dom@14804

npm i https://pkg.pr.new/@vue/runtime-dom@14804

yarn add https://pkg.pr.new/@vue/runtime-dom@14804.tgz

@vue/server-renderer

pnpm add https://pkg.pr.new/@vue/server-renderer@14804

npm i https://pkg.pr.new/@vue/server-renderer@14804

yarn add https://pkg.pr.new/@vue/server-renderer@14804.tgz

@vue/shared

pnpm add https://pkg.pr.new/@vue/shared@14804

npm i https://pkg.pr.new/@vue/shared@14804

yarn add https://pkg.pr.new/@vue/shared@14804.tgz

vue

pnpm add https://pkg.pr.new/vue@14804

npm i https://pkg.pr.new/vue@14804

yarn add https://pkg.pr.new/vue@14804.tgz

@vue/compat

pnpm add https://pkg.pr.new/@vue/compat@14804

npm i https://pkg.pr.new/@vue/compat@14804

yarn add https://pkg.pr.new/@vue/compat@14804.tgz

commit: 1065869

[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: f8fc917e-cb91-4727-9670-7045f597f91a

📥 Commits

Reviewing files that changed from the base of the PR and between 57545e9 and 7344e16.

📒 Files selected for processing (2)

• packages/server-renderer/__tests__/ssrSuspense.spec.ts
• packages/server-renderer/src/helpers/ssrRenderSuspense.ts

---

📝 Walkthrough

Walkthrough

The pull request makes ssrRenderSuspense synchronous instead of async to ensure synchronous errors thrown during server-side Suspense rendering propagate correctly to renderToString. When compiled code calls an async function without awaiting it, any Promise rejection is silently discarded; removing the async wrapper causes exceptions to throw immediately. A new test validates this behavior.

Changes

SSR Suspense Error Propagation

Layer / File(s)	Summary
Function Signature & Documentation packages/server-renderer/src/helpers/ssrRenderSuspense.ts	ssrRenderSuspense changes from export async function returning Promise<void> to export function returning void. Documentation comments explain that synchronous behavior is required to prevent compiled output from discarding unawaited Promise rejections.
Runtime Logic packages/server-renderer/src/helpers/ssrRenderSuspense.ts	Existing runtime branching logic (render content if present, else push HTML comment marker) remains unchanged but now executes synchronously.
Test & Imports packages/server-renderer/__tests__/ssrSuspense.spec.ts	Imports are updated to include defineComponent and ssrRenderSuspense. A new test case asserts that synchronous exceptions thrown by a compiled ssrRenderSuspense default slot callback propagate correctly and cause renderToString to reject with the thrown error.

🎯 2 (Simple) | ⏱️ ~12 minutes

🐰 A function shed its async coat,
So errors won't sail away in a boat,
Now renderToString will see the mistake,
No swallowed rejections to undertake! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: fixing synchronous error propagation from ssrRenderSuspense, which is the primary objective of the changeset.
Linked Issues check	✅ Passed	The pull request addresses the core requirement from issue #28162 by ensuring that synchronous rendering errors in SSR are propagated instead of being swallowed by async machinery.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing SSR error propagation: modifying ssrRenderSuspense to be synchronous and adding a test to verify error handling.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

Review ran into problems

🔥 Problems

Git: Failed to clone repository. Please run the @coderabbitai full review command to re-trigger a full review. If the issue persists, set path_filters to include or exclude specific files.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	106 kB	40 kB	36 kB
vue.global.prod.js	164 kB	60 kB	53.4 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	48.7 kB	18.9 kB	17.3 kB
createApp	56.8 kB	22 kB	20.1 kB
createSSRApp	61.1 kB	23.7 kB	21.6 kB
defineCustomElement	63 kB	23.9 kB	21.8 kB
overall	71.6 kB	27.4 kB	25 kB

[edison1105]

/ecosystem-ci run

[vue-bot]

📝 Ran ecosystem CI: Open

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