[lexical-table][lexical-y] Bug Fix: Don't throw when a table exists before its DOM by zurfyx · Pull Request #9501 · meta/lexical

zurfyx · 2026-10-28T22:27:50Z

Description

Building an editor throws TableObserver: Expected to find TableElement in DOM for key N when the editor state already holds a table before TableExtension registers and the editor has no root element yet. registerTableSelectionObserver registers its TableNode mutation listener with skipInitialization: false, so it receives created for every existing table at registration, and $getTableAndElementByKey asserts that the table's DOM exists.

Any extension listed before TableExtension that sets content in its register hits this. For example, YCollabExtension reads a Y.Doc that already holds a table (a remount, a doc loaded from storage, or a provider that synced first):

buildEditorFromExtensions(
  defineExtension({
    dependencies: [
      RichTextExtension,
      configExtension(YCollabExtension, {doc}),
      TableExtension,
    ],
    name: 'app',
  }),
);

So does any earlier extension that calls editor.setEditorState(...) with a table, or a direct call to registerTableSelectionObserver on an unrendered editor. Listing TableExtension first avoided it, but nothing documented that order.

With this change, the observer skips a table that has no DOM and drops any observer it still holds for that key. When the table is rendered, for example by setRootElement's full reconcile, the reconciler reports it as created, and the observer attaches then. A table with DOM is handled as before.

The fix is in the observer rather than in @lexical/y, which could defer its initial read until every extension has registered. A deferred read would change when the binding's content is available to the rest of the editor. It would also leave the observer throwing for every other source of pre-render content.

Changeset

.changeset/table-observer-unrendered-table.md (@lexical/table: patch, [fix]).

Test plan

New tests:

packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts, with no collaboration:
- an extension listed before TableExtension sets a state holding a table in its register;
- the observer attaches when a root element renders the table, and again on the new DOM when the root is replaced;
- registerTableSelectionObserver on a createEditor editor whose table is not rendered yet.
packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts: a document that already holds a table opens with either extension listed first.

./node_modules/.bin/vitest --run --project unit packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts

Before

× builds when an earlier extension sets a state holding a table during register 14ms
× observes the table once a root element renders it 1ms
× observes the new table DOM when the root element is replaced 1ms
× registerTableSelectionObserver accepts an unrendered table 1ms
× opens a document that holds a table with YCollabExtension listed first 26ms
✓ opens a document that holds a table with TableExtension listed first 4ms
⎯⎯⎯⎯⎯⎯⎯ Failed Tests 5 ⎯⎯⎯⎯⎯⎯⎯
Error: TableObserver: Expected to find TableElement in DOM for key 19
Error: TableObserver: Expected to find TableElement in DOM for key 49
Error: TableObserver: Expected to find TableElement in DOM for key 79
Error: TableObserver: Expected to find TableElement in DOM for key 91
Error: TableObserver: Expected to find TableElement in DOM for key 15
      Tests  5 failed | 1 passed (6)

After

✓ |unit| packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts (4 tests) 187ms
✓ |unit| packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts (2 tests) 111ms
      Tests  6 passed (6)

Also run with the fix:

@lexical/table unit tests: 23 files, 229 tests passed. The new file is 4 of them.
@lexical/y unit tests: 149 files passed and 2 skipped; 4,915 tests passed, 16 expected fail, 2 skipped.
Full unit suite: 540 files passed and 3 skipped; 11,754 tests passed, 16 expected fail, 4 skipped.
Playground Tables.spec.mjs e2e on Chromium: 86 passed, 1 skipped.
pnpm run ci-check passes.
Not run: Firefox and WebKit e2e, and browser-mode unit tests. The change only affects tables that have no DOM, which no browser test renders.

…efore its DOM ## Description Building an editor throws `TableObserver: Expected to find TableElement in DOM for key N` when the editor state already holds a table before `TableExtension` registers and the editor has no root element yet. `registerTableSelectionObserver` registers its `TableNode` mutation listener with `skipInitialization: false`, so it receives `created` for every existing table at registration, and `$getTableAndElementByKey` asserts that the table's DOM exists. Any extension listed before `TableExtension` that sets content in its `register` hits this. For example, `YCollabExtension` reads a `Y.Doc` that already holds a table (a remount, a doc loaded from storage, or a provider that synced first): ```ts buildEditorFromExtensions( defineExtension({ dependencies: [ RichTextExtension, configExtension(YCollabExtension, {doc}), TableExtension, ], name: 'app', }), ); ``` So does any earlier extension that calls `editor.setEditorState(...)` with a table, or a direct call to `registerTableSelectionObserver` on an unrendered editor. Listing `TableExtension` first avoided it, but nothing documented that order. With this change, the observer skips a table that has no DOM and drops any observer it still holds for that key. When the table is rendered, for example by `setRootElement`'s full reconcile, the reconciler reports it as `created`, and the observer attaches then. A table with DOM is handled as before. The fix is in the observer rather than in `@lexical/y`, which could defer its initial read until every extension has registered. A deferred read would change when the binding's content is available to the rest of the editor. It would also leave the observer throwing for every other source of pre-render content. ## Test plan New tests: - `packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts`, with no collaboration: - an extension listed before `TableExtension` sets a state holding a table in its `register`; - the observer attaches when a root element renders the table, and again on the new DOM when the root is replaced; - `registerTableSelectionObserver` on a `createEditor` editor whose table is not rendered yet. - `packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts`: a document that already holds a table opens with either extension listed first. `./node_modules/.bin/vitest --run --project unit packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts` ### Before ``` × builds when an earlier extension sets a state holding a table during register 14ms × observes the table once a root element renders it 1ms × observes the new table DOM when the root element is replaced 1ms × registerTableSelectionObserver accepts an unrendered table 1ms × opens a document that holds a table with YCollabExtension listed first 26ms ✓ opens a document that holds a table with TableExtension listed first 4ms ⎯⎯⎯⎯⎯⎯⎯ Failed Tests 5 ⎯⎯⎯⎯⎯⎯⎯ Error: TableObserver: Expected to find TableElement in DOM for key 19 Error: TableObserver: Expected to find TableElement in DOM for key 49 Error: TableObserver: Expected to find TableElement in DOM for key 79 Error: TableObserver: Expected to find TableElement in DOM for key 91 Error: TableObserver: Expected to find TableElement in DOM for key 15 Tests 5 failed | 1 passed (6) ``` ### After ``` ✓ |unit| packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts (4 tests) 187ms ✓ |unit| packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts (2 tests) 111ms Tests 6 passed (6) ``` Also run with the fix: - `@lexical/table` unit tests: 23 files, 229 tests passed. The new file is 4 of them. - `@lexical/y` unit tests: 149 files passed and 2 skipped; 4,915 tests passed, 16 expected fail, 2 skipped. - Full unit suite: 540 files passed and 3 skipped; 11,754 tests passed, 16 expected fail, 4 skipped. - Playground `Tables.spec.mjs` e2e on Chromium: 86 passed, 1 skipped. - `pnpm run ci-check` passes. - Not run: Firefox and WebKit e2e, and browser-mode unit tests. The change only affects tables that have no DOM, which no browser test renders.

vercel · 2026-10-28T22:27:55Z

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etrepum · 2026-10-29T03:51:48Z

+        onError: error => {
+          throw error;
+        },


This is redundant, always the default for buildEditorFromExtensions

Removed in c884a71.

## Description Review feedback on this PR: `buildEditorFromExtensions` already throws from `onError` by default, so the test's own `onError: error => { throw error; }` is redundant. Removed it. The `createEditor` test in `TableSelectionObserverBeforeDOM.test.ts` keeps its `onError`, since `createEditor`'s default only logs. ## Test plan ### After ``` $ npx vitest run --project unit packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts packages/lexical-table/src/__tests__/unit/TableSelectionObserverBeforeDOM.test.ts Test Files 2 passed (2) Tests 6 passed (6) ```

pkg-pr-new · 2026-10-29T14:57:40Z

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commit: c884a71

…stream main into code block word wrap and line numbers ## Description Brings the PR branch up to date with upstream main (8cc9a96, meta#9501). The merge applies without conflicts. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

…maVersion ## Description Rebasing this PR onto `main` brings in two tests that landed after it was written and bind a plain `Y.Doc` without a `schemaVersion`, which this PR's `YCollabExtension` and `@lexical/y/headless` config no longer accept: - `TableOnOpen.test.ts` (#9501): the document is made with `createYDoc` from the seeded state, and the seed and the extension get `schemaVersion: 1`. - `MarkStateBlockType.test.ts` (#9503): both documents are made with `createYDoc`, and the extension gets `schemaVersion: 1`. ## Test plan ### Before ``` $ npx tsc --noEmit -p tsconfig.json packages/lexical-y/src/__tests__/unit/MarkStateBlockType.test.ts(54,44): error TS2741: Property '[createdByCreateYDoc]' is missing in type 'Doc' but required in type 'YDoc'. packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts(58,9): error TS2345: Argument of type '{ extensions: ... }' is not assignable to parameter of type 'HeadlessYConfig'. packages/lexical-y/src/__tests__/unit/TableOnOpen.test.ts(62,55): error TS2741: Property '[createdByCreateYDoc]' is missing in type 'Doc' but required in type 'YDoc'. ``` ### After ``` $ pnpm run ci-check Found 0 errors $ npx vitest run --project unit Test Files 563 passed | 3 skipped (566) Tests 14641 passed | 46 expected fail | 6 skipped (14693) ```

zurfyx requested review from acywatson, ivailop7 and potatowagon as code owners October 28, 2026 22:27

zurfyx requested a review from etrepum as a code owner October 28, 2026 22:27

meta-cla Bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Oct 28, 2026

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zurfyx mentioned this pull request Oct 29, 2026

[lexical-playground][lexical-website][lexical-y] Feature: Keep a bound editor showing what the document holds, and open documents a newer app version wrote read only #9510

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etrepum added the extended-tests Run extended e2e tests on a PR label Oct 29, 2026

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Merged via the queue into main with commit 8cc9a96 Oct 29, 2026
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[lexical-table][lexical-y] Bug Fix: Don't throw when a table exists before its DOM - #9501

[lexical-table][lexical-y] Bug Fix: Don't throw when a table exists before its DOM#9501
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Description

Changeset

Test plan

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