From e2572c21110a3acce200b7dece07d6093eab014a Mon Sep 17 00:00:00 2001
From: Kamil Piechaczek <pomek@users.noreply.github.com>
Date: Mon, 17 Jan 2022 16:11:06 +0100
Subject: [PATCH 1/2] Fixed a crash when removing a content from the last list
 item next to a non-list element.

---
 .../src/listpropertiesediting.js              |  7 +++
 .../tests/listpropertiesediting.js            | 57 +++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/packages/ckeditor5-list/src/listpropertiesediting.js b/packages/ckeditor5-list/src/listpropertiesediting.js
index 0d52b6006e4..ac991301d55 100644
--- a/packages/ckeditor5-list/src/listpropertiesediting.js
+++ b/packages/ckeditor5-list/src/listpropertiesediting.js
@@ -214,6 +214,13 @@ export default class ListPropertiesEditing extends Plugin {
 					direction: 'forward'
 				} );
 
+				// If the selection ends in a non-list element, there are no <listItem>s that would require adjustments.
+				// See: #8642.
+				if ( !secondListMostOuterItem ) {
+					firstMostOuterItem = null;
+					return;
+				}
+
 				const items = [
 					secondListMostOuterItem,
 					...getSiblingNodes( writer.createPositionAt( secondListMostOuterItem, 0 ), 'forward' )
diff --git a/packages/ckeditor5-list/tests/listpropertiesediting.js b/packages/ckeditor5-list/tests/listpropertiesediting.js
index 3146cc87d87..6a8654044b7 100644
--- a/packages/ckeditor5-list/tests/listpropertiesediting.js
+++ b/packages/ckeditor5-list/tests/listpropertiesediting.js
@@ -1530,6 +1530,25 @@ describe( 'ListPropertiesEditing', () => {
 					);
 				} );
 
+				// See: #8642.
+				it( 'should not crash when removing entire list item followed by a paragraph element with another list', () => {
+					setModelData( model,
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">aaaa</listItem>' +
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">[bbbb</listItem>' +
+						'<paragraph>]foo</paragraph>' +
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">aaaa</listItem>'
+					);
+
+					editor.execute( 'delete' );
+
+					expect( getModelData( model ) ).to.equal(
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">aaaa</listItem>' +
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">[]</listItem>' +
+						'<paragraph>foo</paragraph>' +
+						'<listItem listIndent="0" listStyle="default" listType="bulleted">aaaa</listItem>'
+					);
+				} );
+
 				function simulateTyping( text ) {
 				// While typing, every character is an atomic change.
 					text.split( '' ).forEach( character => {
@@ -3198,6 +3217,25 @@ describe( 'ListPropertiesEditing', () => {
 					);
 				} );
 
+				// See: #8642.
+				it( 'should not crash when removing entire list item followed by a paragraph element with another list', () => {
+					setModelData( model,
+						'<listItem listIndent="0" listReversed="true" listType="numbered">aaaa</listItem>' +
+						'<listItem listIndent="0" listReversed="true" listType="numbered">[bbbb</listItem>' +
+						'<paragraph>]foo</paragraph>' +
+						'<listItem listIndent="0" listReversed="true" listType="numbered">aaaa</listItem>'
+					);
+
+					editor.execute( 'delete' );
+
+					expect( getModelData( model ) ).to.equal(
+						'<listItem listIndent="0" listReversed="true" listType="numbered">aaaa</listItem>' +
+						'<listItem listIndent="0" listReversed="true" listType="numbered">[]</listItem>' +
+						'<paragraph>foo</paragraph>' +
+						'<listItem listIndent="0" listReversed="true" listType="numbered">aaaa</listItem>'
+					);
+				} );
+
 				it(
 					'should read the `listReversed` attribute from the most outer selected list while removing content between lists',
 					() => {
@@ -4828,6 +4866,25 @@ describe( 'ListPropertiesEditing', () => {
 					);
 				} );
 
+				// See: #8642.
+				it( 'should not crash when removing entire list item followed by a paragraph element with another list', () => {
+					setModelData( model,
+						'<listItem listIndent="0" listStart="1" listType="numbered">aaaa</listItem>' +
+						'<listItem listIndent="0" listStart="1" listType="numbered">[bbbb</listItem>' +
+						'<paragraph>]foo</paragraph>' +
+						'<listItem listIndent="0" listStart="1" listType="numbered">aaaa</listItem>'
+					);
+
+					editor.execute( 'delete' );
+
+					expect( getModelData( model ) ).to.equal(
+						'<listItem listIndent="0" listStart="1" listType="numbered">aaaa</listItem>' +
+						'<listItem listIndent="0" listStart="1" listType="numbered">[]</listItem>' +
+						'<paragraph>foo</paragraph>' +
+						'<listItem listIndent="0" listStart="1" listType="numbered">aaaa</listItem>'
+					);
+				} );
+
 				it(
 					'should read the `listStart` attribute from the most outer selected list while removing content between lists',
 					() => {

From 28d6ff5ea3623d2fe924d49ec09d33435831a2d3 Mon Sep 17 00:00:00 2001
From: Kamil Piechaczek <pomek@users.noreply.github.com>
Date: Mon, 17 Jan 2022 16:18:57 +0100
Subject: [PATCH 2/2] Travis, come on.