ecency · feruzm · Apr 11, 2026 · Apr 11, 2026 · Apr 11, 2026 · Apr 11, 2026
diff --git a/packages/render-helper/CHANGELOG.md b/packages/render-helper/CHANGELOG.md
@@ -1,5 +1,11 @@
 # @ecency/render-helper
 
+## 2.4.30
+
+### Patch Changes
+
+- Dom parser improvement (#753)
+
 ## 2.4.29
 
 ### Patch Changes

diff --git a/packages/render-helper/dist/browser/index.js b/packages/render-helper/dist/browser/index.js
diff --git a/packages/render-helper/dist/browser/index.js.map b/packages/render-helper/dist/browser/index.js.map
diff --git a/packages/render-helper/dist/node/index.cjs b/packages/render-helper/dist/node/index.cjs
@@ -231,8 +231,11 @@ function createDoc(html) {
     return null;
   }
   const cleanedHtml = removeDuplicateAttributes(html);
-  const doc = DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, "text/html");
-  return doc;
+  try {
+    return DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, "text/html");
+  } catch {
+    return null;
+  }
 }
 function makeEntryCacheKey(entry) {
   return `${entry.author}-${entry.permlink}-${entry.last_update}-${entry.updated}`;

diff --git a/packages/render-helper/dist/node/index.cjs.map b/packages/render-helper/dist/node/index.cjs.map
diff --git a/packages/render-helper/dist/node/index.mjs b/packages/render-helper/dist/node/index.mjs
@@ -202,8 +202,11 @@ function createDoc(html) {
     return null;
   }
   const cleanedHtml = removeDuplicateAttributes(html);
-  const doc = DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, "text/html");
-  return doc;
+  try {
+    return DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, "text/html");
+  } catch {
+    return null;
+  }
 }
 function makeEntryCacheKey(entry) {
   return `${entry.author}-${entry.permlink}-${entry.last_update}-${entry.updated}`;

diff --git a/packages/render-helper/dist/node/index.mjs.map b/packages/render-helper/dist/node/index.mjs.map
diff --git a/packages/render-helper/package.json b/packages/render-helper/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@ecency/render-helper",
   "private": false,
-  "version": "2.4.29",
+  "version": "2.4.30",
   "description": "Markdown+Html Render helper",
   "repository": {
     "type": "git",

diff --git a/packages/render-helper/src/helper.spec.ts b/packages/render-helper/src/helper.spec.ts
@@ -432,6 +432,44 @@ describe('Helper Functions', () => {
       expect(imgs?.length).toBeGreaterThan(0)
       expect(brs?.length).toBeGreaterThan(0)
     })
+
+    // Regression: @xmldom/xmldom 0.9+ throws a fatal ParseError on severely
+    // malformed HTML (e.g., a <p> that fails to close before </body>). The
+    // onError handler can't suppress the throw — only a try/catch in
+    // createDoc can. Before the fix, this crashed SSR for /entry/[...] pages.
+    // See Sentry ECENCY-NEXT-1C86.
+    //
+    // The contract these tests lock in is: createDoc must return `Document | null`
+    // for any input, never throw. Whether a particular malformed snippet parses
+    // successfully (Document) or fails (null) depends on xmldom's recovery
+    // heuristics, which may improve across versions — we deliberately allow
+    // either outcome as long as the return shape matches the type.
+    const expectDocumentOrNull = (result: ReturnType<typeof createDoc>) => {
+      if (result === null) return
+      expect(typeof result.getElementsByTagName).toBe('function')
+    }
+
+    it('should not throw on mismatched body/p tags', () => {
+      // The content ends with an opening <p> that has no closing tag.
+      // Parsing <body>...<p></body> triggers xmldom's fatalError path.
+      const input = '<p>oops<p>hello'
+      expect(() => createDoc(input)).not.toThrow()
+      expectDocumentOrNull(createDoc(input))
+    })
+
+    it('should not throw on deeply malformed HTML', () => {
+      // Nested unclosed tags — another pattern xmldom reports as fatal.
+      const input = '<div><p><span><a><b><i>no closing tags here'
+      expect(() => createDoc(input)).not.toThrow()
+      expectDocumentOrNull(createDoc(input))
+    })
+
+    it('should not throw on invalid XML characters', () => {
+      // Unescaped < followed by non-tag content is a classic fatal-error case.
+      const input = '<div>less than < something</div>'
+      expect(() => createDoc(input)).not.toThrow()
+      expectDocumentOrNull(createDoc(input))
+    })
   })
 
   describe('makeEntryCacheKey', () => {

diff --git a/packages/render-helper/src/helper.ts b/packages/render-helper/src/helper.ts
@@ -48,9 +48,20 @@ export function createDoc(html: string): Document | null {
   // This is needed because markdownToHTML can generate multiple top-level elements
   // (e.g., <center>...</center><hr />) which DOMParser doesn't accept without a wrapper
   // Using <body> instead of <div> prevents conflicts with <div> elements in the content
-  const doc = DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, 'text/html')
-
-  return doc
+  //
+  // @xmldom/xmldom 0.9+ always throws a ParseError from its internal fatalError() path
+  // (see dom-parser.js:490) for severely malformed HTML — e.g., mismatched tags like
+  // <body>...<p>...</body> — regardless of the onError handler returning undefined.
+  // The onError handler only gets to observe; the throw still happens.
+  //
+  // Wrap in try/catch so that pathologically-malformed post bodies degrade gracefully
+  // (no image preload hint) instead of crashing the SSR render of /entry/[...]. Both
+  // callers in catch-post-image.ts already handle a null return.
+  try {
+    return DOMParser.parseFromString(`<body>${cleanedHtml}</body>`, 'text/html')
+  } catch {
+    return null
+  }
 }
 
 export function makeEntryCacheKey(entry: any): string {