fix(utils): prevent sitemap metadata leak across url without loc (#3795)

`SitemapXmlParser` in `packages/utils/src/internals/sitemap.ts` could
leak per-url metadata from a malformed `<url>` block into the next one,
and emitted `Invalid Date` for unparseable `<lastmod>` values. This
PR fixes both.

Author: anxkhn

packages/utils/src/internals/sitemap.ts

@@ -136,8 +136,10 @@ class SitemapXmlParser extends Transform {
             this.currentTag = undefined;
         }
 
-        if (name === 'url' && this.url.loc !== undefined) {
-            this.push({ type: 'url', ...this.url, loc: this.url.loc } satisfies SitemapItem);
+        if (name === 'url') {
+            if (this.url.loc !== undefined) {
+                this.push({ type: 'url', ...this.url, loc: this.url.loc } satisfies SitemapItem);
+            }
             this.url = {};
         }
     }
@@ -157,7 +159,10 @@ class SitemapXmlParser extends Transform {
         text = text.trim();
 
         if (this.currentTag === 'lastmod') {
-            this.url.lastmod = new Date(text);
+            const lastmod = new Date(text);
+            if (!Number.isNaN(lastmod.getTime())) {
+                this.url.lastmod = lastmod;
+            }
         }
 
         if (this.currentTag === 'priority') {

packages/utils/test/sitemap.test.ts

@@ -423,6 +423,39 @@ describe('Sitemap', () => {
         );
     });
 
+    it('does not leak metadata from a url without loc and drops invalid lastmod', async () => {
+        const items: SitemapUrl[] = [];
+
+        for await (const item of parseSitemap([
+            {
+                type: 'raw',
+                content: [
+                    '<?xml version="1.0" encoding="UTF-8"?>',
+                    '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">',
+                    '<url>',
+                    '<loc>http://not-exists.com/a</loc>',
+                    '<lastmod>not-a-date</lastmod>',
+                    '</url>',
+                    '<url>',
+                    '<lastmod>2020-01-01</lastmod>',
+                    '<priority>0.5</priority>',
+                    '</url>',
+                    '<url>',
+                    '<loc>http://not-exists.com/c</loc>',
+                    '</url>',
+                    '</urlset>',
+                ].join('\n'),
+            },
+        ])) {
+            items.push(item);
+        }
+
+        expect(items.map((item) => item.loc)).toEqual(['http://not-exists.com/a', 'http://not-exists.com/c']);
+        expect(items[0].lastmod).toBeUndefined();
+        expect(items[1].lastmod).toBeUndefined();
+        expect(items[1].priority).toBeUndefined();
+    });
+
     it('loads sitemaps that reference other sitemaps from string', async () => {
         const sitemap = await Sitemap.fromXmlString(
             [