Merge pull request #1741 from lightpanda-io/DOMParser_invalid_xml

Throw exception, as expected, on empty input to DOMParser.parseFromSt…

src/browser/tests/domparser.html

@@ -4,9 +4,17 @@
 
 <script id=basic>
 {
+  {
     const parser = new DOMParser();
     testing.expectEqual('object', typeof parser);
     testing.expectEqual('function', typeof parser.parseFromString);
+  }
+
+  {
+    // Empty XML is a parse error (no root element)
+    const parser = new DOMParser();
+    testing.expectError('Error', () => parser.parseFromString('', 'text/xml'));
+  }
 }
 </script>
 

src/browser/webapi/DOMParser.zig

@@ -90,15 +90,16 @@ pub fn parseFromString(
                 return pe.err;
             }
 
-            // If first node is a `ProcessingInstruction`, skip it.
             const first_child = doc_node.firstChild() orelse {
-                // Parsing should fail if there aren't any nodes.
-                unreachable;
+                // Empty XML or no root element - this is a parse error.
+                // TODO: Return a document with a <parsererror> element per spec.
+                return error.JsException;
             };
 
+            // If first node is a `ProcessingInstruction`, skip it.
             if (first_child.getNodeType() == 7) {
                 // We're sure that firstChild exist, this cannot fail.
-                _ = doc_node.removeChild(first_child, page) catch unreachable;
+                _ = try doc_node.removeChild(first_child, page);
             }
 
             return doc.asDocument();