RangeError in getParentBlockInfo when pressing Delete at end of last block (regression from #2126)

[hedi-ghodhbane]

What's broken?

Pressing the Delete key (forward-delete) when the cursor is at the end of the last block in the document throws:

RangeError: There is no position before the top-level node

The error originates from getParentBlockInfo in mergeBlocks.ts (line 16).

This is a regression introduced in PR #2126 (v0.47.1). The old code had a depth guard:

if ($pos.depth <= 1) {
    return undefined;
}

The new code calls $pos.before(depth) before any guard:

const depth = $pos.depth - 1;
const parentBeforePos = $pos.before(depth); // crashes when depth === 0

When $pos.depth === 1, depth becomes 0, and $pos.before(0) throws because there is no position before the top-level document node.

What did you expect to happen?

Pressing Delete at the end of the last block should be a no-op (nothing to merge with), not throw an uncaught RangeError.

Steps to reproduce

1. Open any BlockNote editor
2. Type some text in a single block (e.g. "hello")
3. Place cursor at the end of the text
4. Press the Delete key (Fn+Backspace on Mac)
5. Open browser DevTools console → RangeError: There is no position before the top-level node

Or paste this in the browser console on any page with a BlockNote editor:

(() => {
  const el = document.querySelector('[contenteditable="true"]');
  if (!el) return console.error('No editor found');
  el.focus();
  document.execCommand('insertText', false, 'hello');
  const sel = window.getSelection();
  sel.selectAllChildren(el);
  sel.collapseToEnd();
  el.dispatchEvent(new KeyboardEvent('keydown', { key: 'Delete', code: 'Delete', bubbles: true }));
  console.log('Check console for RangeError');
})();

Suggested fix

Restore the depth guard before calling $pos.before(depth) in getParentBlockInfo:

export const getParentBlockInfo = (doc: Node, beforePos: number): BlockInfo | undefined => {
  const $pos = doc.resolve(beforePos);
  const depth = $pos.depth - 1;

  if (depth < 1) {
    return undefined;
  }

  const parentBeforePos = $pos.before(depth);
  // ...rest of function
};

BlockNote version

0.47.1

Environment

All browsers (Chrome, Firefox, Safari). Reproducible in both browser and jsdom (vitest).

Additional context

Related to #2452 and #2453. PR #2126 fixed forward-delete for most cases but introduced this regression for the last-block edge case.

Contribution

• I'd be interested in contributing a fix for this issue

Sponsor

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