fix: handle renderer.run rejections#17591
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Rich-Harris merged 5 commits intosveltejs:mainfrom Jan 30, 2026
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🦋 Changeset detectedLatest commit: 06989f3 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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Rich-Harris
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* fix: handle renderer run rejections * add test * changeset * simplify * explanatory comment --------- Co-authored-by: Antonio Bennett <abennett@mabelslabels.com> Co-authored-by: Rich Harris <rich.harris@vercel.com>
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* fix: emit `each_key_duplicate` error in production * fix: preserve key * Update packages/svelte/src/internal/client/dom/blocks/each.js Co-authored-by: Rich Harris <rich.harris@vercel.com> * Update packages/svelte/src/internal/client/dom/blocks/each.js Co-authored-by: Rich Harris <rich.harris@vercel.com> * fix: ensure keys are validated * fix silly test name * fix: cover other case of duplicate keys * emit error on hydration * ensure the error is handled * drop useless tests * unused * finish merge * add lost check back * chore: bump playwright (#17565) * chore: bump playwright * maybe this will help somehow? * err whatever * fix * chore: allow testing in production env 2 (#17590) * Revert "chore: allow testing in production env (#16840)" This reverts commit ffd65e9. * new approach * fix: handle renderer.run rejections (#17591) * fix: handle renderer run rejections * add test * changeset * simplify * explanatory comment --------- Co-authored-by: Antonio Bennett <abennett@mabelslabels.com> Co-authored-by: Rich Harris <rich.harris@vercel.com> * fix: only create async functions in SSR output when necessary (#17593) * fix: only create async functions in SSR output when necessary * actually... * simplify generated code a bit more * simplify * fix: merge consecutive text nodes during hydration for large text content (#17587) * fix: merge consecutive text nodes during hydration for large text content Fixes #17582 Browsers automatically split text nodes exceeding 65536 characters into multiple consecutive text nodes during HTML parsing. This causes hydration mismatches when Svelte expects a single text node. The fix merges consecutive text nodes during hydration by: - Detecting when the current node is a text node - Finding all consecutive text node siblings - Merging their content into the first text node - Removing the extra text nodes This restores correct hydration behavior for large text content. * add test, fix * fix * fix * changeset --------- Co-authored-by: Miner <miner@example.com> Co-authored-by: Rich Harris <rich.harris@vercel.com> * Version Packages (#17585) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> * Revert "drop useless tests" This reverts commit 65f77ef. * update tests * fix test * we don't need to expose this function any more * figured it out... we cant have errors during reconcile * simplify * tweak * unused * revert no-longer-needed change * unused --------- Co-authored-by: Rich Harris <rich.harris@vercel.com> Co-authored-by: Antonio Bennett <31296212+Antonio-Bennett@users.noreply.github.com> Co-authored-by: Antonio Bennett <abennett@mabelslabels.com> Co-authored-by: FORMI <239411042+Richman018@users.noreply.github.com> Co-authored-by: Miner <miner@example.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Summary
Renderer.run()as handled to prevent unhandled rejectionsrenderer.promiseso async SSR waits for itContext
Renderer.run()starts async work and returns the promise chain, but the work isn’t associated withrenderer.promiseand no rejection handler is attached. When a render-timeRedirect(or other error) happens before the render is awaited, Node reports an unhandled rejection. This adds a no-op catch to mark the chain as handled and wires it into the renderer’s async tracking so the rejection still surfaces when awaited.How This Relates To SvelteKit
This addresses the root unhandled-rejection cause observed in SvelteKit when a render-time
redirect()happens (e.g. via remotequery). The companion Kit PR (linked below) handlesRedirectduring render so it becomes a proper redirect response rather than a 500.Notes
Related
Test Plan
redirect()(via SvelteKit remote query) no longer triggers unhandled rejection