fix(core): don't throw when the placeholder style is already removed by adarshsm · Pull Request #3145 · TypeCellOS/BlockNote

adarshsm · 2026-10-02T04:36:41Z

Summary

Closes #3144. Destroying an editor throws NotFoundError: Failed to execute 'removeChild' on 'Node' when the Placeholder extension's <style> element was already removed from <head> (or the shadow root) by something else, e.g. Hotwire Turbo merging the next page's <head> and dropping duplicate empty <style> elements.

Rationale

The Placeholder plugin view's destroy called view.root.removeChild(styleEl) / view.root.head.removeChild(styleEl), which throws if the element is no longer a child. Because it throws inside ProseMirror's EditorView.destroyPluginViews, the rest of that editor's teardown (remaining plugin views, the doc view) is skipped too.

Changes

packages/core/src/extensions/Placeholder/Placeholder.ts: use styleEl.remove() in destroy. It removes the element from whatever parent it has (document head or shadow root) and is a no-op if it has none, so both branches collapse into one.

Impact

No behaviour change when the style element is still attached. When it was already detached, unmounting no longer throws and the editor tears down fully.

Testing

New packages/core/src/extensions/Placeholder/Placeholder.test.ts: mounts an editor, removes its placeholder <style> from <head>, and checks that editor.unmount() doesn't throw.
Verified it fails on main (DOMException NotFoundError thrown) and passes with the fix.
vp test --run src/extensions/Placeholder src/editor/BlockNoteEditor.test.ts src/comments in packages/core passes (3 files / 18 tests). vp lint and vp fmt are clean on the changed files.
I couldn't run the Docker browser suite on this machine.

Checklist

Code follows the project's coding standards.
Unit tests covering the new feature have been added.
All existing tests pass.
The documentation has been updated to reflect the new feature (n/a)

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Improved placeholder stylesheet cleanup to prevent errors when an editor is unmounted after the stylesheet has been removed.

The Placeholder plugin view removed its <style> on destroy with removeChild, which throws NotFoundError if something else (e.g. Turbo merging <head> and dropping duplicate empty <style> elements) detached it first. The throw also aborts the rest of ProseMirror's view teardown. Use styleEl.remove(), which is a no-op when the element has no parent and covers both the document and shadow root cases. Closes TypeCellOS#3144

vercel · 2026-10-02T04:36:46Z

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coderabbitai · 2026-10-02T04:36:48Z

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Reviewing files that changed from the base of the PR and between f64d544 and dc9b9da.

📒 Files selected for processing (2)

packages/core/src/extensions/Placeholder/Placeholder.test.ts
packages/core/src/extensions/Placeholder/Placeholder.ts

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📝 Walkthrough

Walkthrough

The Placeholder view now removes its style element with styleEl.remove(). A regression test removes the style element before editor unmount and checks that unmount does not throw.

Changes

Placeholder cleanup

Layer / File(s)	Summary
Style cleanup and regression test `packages/core/src/extensions/Placeholder/Placeholder.ts`, `packages/core/src/extensions/Placeholder/Placeholder.test.ts`	The destroy callback uses `styleEl.remove()` instead of separate Shadow DOM and document-root removal calls. The test removes the placeholder stylesheet before unmount and asserts that unmount does not throw.

Priority: ➖ Normal

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to dc9b9

The change makes editor teardown tolerate an already-removed placeholder stylesheet, with a regression test for that case. No merge-blocking risk is evident in the supplied context.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main fix: preventing teardown errors when the placeholder style element was already removed.
Description check	✅ Passed	The description includes all required sections, explains the issue and rationale, lists the code and test changes, documents impact and testing, and records the checklist status. Screenshots are not a…
Linked Issues check	✅ Passed	Issue `#3144` requires editor destruction to avoid `NotFoundError` when the Placeholder `<style>` element was detached. `Placeholder.ts` now calls `styleEl.remove()`, which is a no-op when the element h…
Out of Scope Changes check	✅ Passed	The pull request changes only Placeholder style cleanup and adds a regression test for issue `#3144`. Both changes directly support the linked issue. No unrelated changes are shown.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…

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_{A rabbit watched the style tag go,
Then saw remove() let teardown flow.
The editor unmounted without a throw,
No missing-node complaint below.
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pkg-pr-new · 2026-10-02T04:43:22Z

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commit: dc9b9da

vercel · 2026-10-02T13:23:47Z

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blocknote	Ready	Preview	Oct 2, 2026 1:26pm UTC
blocknote-website	Ready	Preview	Oct 2, 2026 1:26pm UTC

matthewlipski · 2026-10-02T13:57:12Z

Thanks!

matthewlipski marked this pull request as ready for review October 2, 2026 13:24

vercel Bot deployed to Preview – blocknote October 2, 2026 13:24 View deployment

vercel Bot deployed to Preview – blocknote-website October 2, 2026 13:26 View deployment

matthewlipski merged commit c6f14b0 into TypeCellOS:main Oct 2, 2026
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fix(core): don't throw when the placeholder style is already removed - #3145

fix(core): don't throw when the placeholder style is already removed#3145
matthewlipski merged 1 commit into
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adarshsm:fix/3144-placeholder-destroy

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