From 2f8e37805fb6debffad346a4fc20c4384929959f Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Fri, 3 Apr 2026 07:11:08 +0100
Subject: [PATCH] fix: prevent crash when pasting bare <li> without parent list
 element (#7431)

When HTML containing <li> elements without a wrapping <ul> or <ol> is
pasted (e.g., from ChatGPT), the contentcollector crashes with
"TypeError: lineAttributes.list is undefined" because it assumes
_enterList() was already called by a parent list element.

The fix defaults bare <li> elements to bullet1 list type and properly
sets oldListTypeOrNull so the list state is cleaned up after the <li>
is processed. Also guards the .indexOf() call on lineAttributes.list.

Fixes: https://github.com/ether/etherpad-lite/issues/6665

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 src/static/js/contentcollector.ts           |  7 +++++-
 src/tests/backend/specs/contentcollector.ts | 27 +++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/src/static/js/contentcollector.ts b/src/static/js/contentcollector.ts
index 5b9d7f362..a2140d6fd 100644
--- a/src/static/js/contentcollector.ts
+++ b/src/static/js/contentcollector.ts
@@ -504,9 +504,14 @@ const makeContentCollector = (collectStyles, abrowser, apool, className2Author)
             // See https://github.com/ether/etherpad-lite/issues/2412 for reasoning
             if (!abrowser.chrome) oldListTypeOrNull = (_enterList(state, undefined) || 'none');
           } else if (tname === 'li') {
+            // If the <li> has no parent <ul>/<ol> (e.g., pasted bare HTML), default to bullet list.
+            // See https://github.com/ether/etherpad-lite/issues/6665
+            if (!state.lineAttributes.list) {
+              oldListTypeOrNull = (_enterList(state, 'bullet1') || 'none');
+            }
             state.lineAttributes.start = state.start || 0;
             _recalcAttribString(state);
-            if (state.lineAttributes.list.indexOf('number') !== -1) {
+            if (state.lineAttributes.list && state.lineAttributes.list.indexOf('number') !== -1) {
               /*
                Nested OLs are not --> <ol><li>1</li><ol>nested</ol></ol>
                They are           --> <ol><li>1</li><li><ol><li>nested</li></ol></li></ol>
diff --git a/src/tests/backend/specs/contentcollector.ts b/src/tests/backend/specs/contentcollector.ts
index 50178fbae..f7b7a3adf 100644
--- a/src/tests/backend/specs/contentcollector.ts
+++ b/src/tests/backend/specs/contentcollector.ts
@@ -332,6 +332,33 @@ pre
     wantAlines: ['+f*1+2+2'],
     wantText: ['Need more space s !'],
   },
+  {
+    description: 'Bare <li> without parent <ul>/<ol> should not crash (bug #6665)',
+    html: '<html><body><li>this should not crash</li></body></html>',
+    wantAlines: [
+      '*0*2*6+1+l',
+    ],
+    wantText: ['*this should not crash'],
+  },
+  {
+    description: 'Multiple bare <li> elements without parent list',
+    html: '<html><body><li>first</li><li>second</li></body></html>',
+    wantAlines: [
+      '*0*2*6+1+5',
+      '*0*2*6+1+6',
+    ],
+    wantText: ['*first', '*second'],
+  },
+  {
+    description: 'Mixed bare <li> and normal content',
+    html: '<html><body><p>before</p><li>bare item</li><p>after</p></body></html>',
+    wantAlines: [
+      '+6',
+      '*0*2*6+1+9',
+      '+5',
+    ],
+    wantText: ['before', '*bare item', 'after'],
+  },
 ];
 
 describe(__filename, function () {
