From a204f4096803dc7bd60fd1ed542f3eb8828bc93b Mon Sep 17 00:00:00 2001
From: sjhddh <jhao.sun@gmail.com>
Date: Sat, 14 Mar 2026 08:36:06 +0000
Subject: [PATCH 1/2] fix(dom): return parsererror document on XML parse
 failure

---
 src/browser/webapi/DOMParser.zig | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/browser/webapi/DOMParser.zig b/src/browser/webapi/DOMParser.zig
index 9e27e9c7..10a94bca 100644
--- a/src/browser/webapi/DOMParser.zig
+++ b/src/browser/webapi/DOMParser.zig
@@ -86,15 +86,15 @@ pub fn parseFromString(
             var parser = Parser.init(arena, doc_node, page);
             parser.parseXML(html);
 
-            if (parser.err) |pe| {
-                return pe.err;
+            if (parser.err != null or doc_node.firstChild() == null) {
+                // Return a document with a <parsererror> element per spec.
+                const err_doc = try page._factory.document(XMLDocument{ ._proto = undefined });
+                var err_parser = Parser.init(arena, err_doc.asNode(), page);
+                err_parser.parseXML("<parsererror xmlns=\"http://www.mozilla.org/newlayout/xml/parsererror.xml\">error</parsererror>");
+                return err_doc.asDocument();
             }
 
-            const first_child = doc_node.firstChild() orelse {
-                // Empty XML or no root element - this is a parse error.
-                // TODO: Return a document with a <parsererror> element per spec.
-                return error.JsException;
-            };
+            const first_child = doc_node.firstChild().?;
 
             // If first node is a `ProcessingInstruction`, skip it.
             if (first_child.getNodeType() == 7) {

From 0eb43fb53062bc20521e2dcadc7328fae665712c Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Mon, 16 Mar 2026 07:16:27 +0800
Subject: [PATCH 2/2] Fix test

Fixes test associated with https://github.com/lightpanda-io/browser/pull/1827
---
 src/browser/tests/domparser.html | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/browser/tests/domparser.html b/src/browser/tests/domparser.html
index 7930ec87..d8399055 100644
--- a/src/browser/tests/domparser.html
+++ b/src/browser/tests/domparser.html
@@ -11,9 +11,9 @@
   }
 
   {
-    // Empty XML is a parse error (no root element)
     const parser = new DOMParser();
-    testing.expectError('Error', () => parser.parseFromString('', 'text/xml'));
+    let d = parser.parseFromString('', 'text/xml');
+    testing.expectEqual('<parsererror>error</parsererror>', new XMLSerializer().serializeToString(d));
   }
 }
 </script>