From 2b1f4395b33e73030acf587cb312b7e826d52967 Mon Sep 17 00:00:00 2001
From: lucaronin <luca.rossi.917@gmail.com>
Date: Sat, 6 Jun 2026 03:57:21 +0200
Subject: [PATCH] fix: recover null editor transform errors

---
 ...hEditorTransformErrorRecoveryExtension.test.ts | 15 +++++++++++++++
 .../richEditorTransformErrorRecoveryExtension.ts  | 14 +++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/components/richEditorTransformErrorRecoveryExtension.test.ts b/src/components/richEditorTransformErrorRecoveryExtension.test.ts
index e6aceec3..601307cd 100644
--- a/src/components/richEditorTransformErrorRecoveryExtension.test.ts
+++ b/src/components/richEditorTransformErrorRecoveryExtension.test.ts
@@ -16,6 +16,10 @@ function transformError(message = 'Invalid transform') {
   return error
 }
 
+function nullFragmentAppendError(message = "null is not an object (evaluating 'o.fillBefore(e).append')") {
+  return new TypeError(message)
+}
+
 function createView(error?: Error) {
   const currentDoc = {
     eq: vi.fn((candidate: unknown) => candidate === currentDoc),
@@ -94,6 +98,10 @@ describe('isRecoverableEditorTransformError', () => {
     expect(isRecoverableEditorTransformError(new Error(
       'Block with ID 6c1c3bb4-e218-4f00-aaf5-40606852d286 not found',
     ))).toBe(true)
+    expect(isRecoverableEditorTransformError(nullFragmentAppendError())).toBe(true)
+    expect(isRecoverableEditorTransformError(new TypeError(
+      "Cannot read properties of null (reading 'append')",
+    ))).toBe(false)
     expect(isRecoverableEditorTransformError(new RangeError(
       'Index 1 out of range for <paragraph("A")>',
     ))).toBe(false)
@@ -213,6 +221,13 @@ describe('installRichEditorTransformErrorRecovery', () => {
     )
   })
 
+  it('repairs null fragment append failures from invalid document model fills', () => {
+    expectDocumentRepairRecovery(
+      nullFragmentAppendError(),
+      'null_fragment_append',
+    )
+  })
+
   it('recovers stale block-reference transactions from toolbar actions', () => {
     const { currentDoc, view } = createView(new Error(
       'Block with ID 6c1c3bb4-e218-4f00-aaf5-40606852d286 not found',
diff --git a/src/components/richEditorTransformErrorRecoveryExtension.ts b/src/components/richEditorTransformErrorRecoveryExtension.ts
index 4b93c9e4..50bebf71 100644
--- a/src/components/richEditorTransformErrorRecoveryExtension.ts
+++ b/src/components/richEditorTransformErrorRecoveryExtension.ts
@@ -48,6 +48,7 @@ type RecoveryReason =
   | 'invalid_block_join'
   | 'invalid_insertion_depth'
   | 'mismatched_transaction'
+  | 'null_fragment_append'
   | 'stale_block_reference'
   | 'stale_transaction'
   | 'table_position_out_of_range'
@@ -95,6 +96,13 @@ function isInvalidBlockJoinError(error: unknown): boolean {
   return isTransformError(error) && /^Cannot join (blockGroup|tableCell) onto blockContainer$/.test(error.message)
 }
 
+function isNullFragmentAppendError(error: unknown): boolean {
+  if (!(error instanceof TypeError)) return false
+
+  const details = `${error.message}\n${error.stack ?? ''}`
+  return details.includes('fillBefore') && details.includes('.append')
+}
+
 export function isStaleBlockReferenceError(error: unknown): boolean {
   return error instanceof Error && /^Block with ID .+ not found$/.test(error.message)
 }
@@ -113,6 +121,7 @@ const RECOVERABLE_EDITOR_ERROR_PREDICATES = [
   isTransformError,
   isMismatchedTransactionError,
   isRecoverableRangeError,
+  isNullFragmentAppendError,
   isStaleBlockReferenceError,
 ]
 
@@ -130,12 +139,15 @@ function recoveryReason(
   if (isStaleBlockReferenceError(error)) return 'stale_block_reference'
   if (isInvalidBlockJoinError(error)) return 'invalid_block_join'
   if (isInvalidInsertionDepthError(error)) return 'invalid_insertion_depth'
+  if (isNullFragmentAppendError(error)) return 'null_fragment_append'
   if (isTablePositionOutOfRangeError(error)) return 'table_position_out_of_range'
   return 'transform_error'
 }
 
 function shouldRepairEditorDocument(error: unknown): boolean {
-  return isRecoverableRangeError(error) || isInvalidBlockJoinError(error)
+  return isRecoverableRangeError(error)
+    || isInvalidBlockJoinError(error)
+    || isNullFragmentAppendError(error)
 }
 
 export const reportRecoveredEditorTransformError = (reason: RecoveryReason, error: unknown): void => {