fix: handle null declaration in DocxExporter to prevent export crash (#2578)

* fix: handle null declaration in DocxExporter to prevent export crash

When exporting a SuperDoc to DOCX, if the converter's declaration is null
(e.g., for documents created/edited via Yjs collaboration without raw XML
import), the export crashes with: TypeError: Cannot read properties of null
(reading 'attributes').

Add optional chaining and a standard XML declaration fallback
(version="1.0" encoding="UTF-8" standalone="yes") so export succeeds when
converter.declaration is null or undefined.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(super-converter): extract DEFAULT_XML_DECLARATION to shared constant

Move the inline XML declaration fallback to constants.js so exporter.js
and citation-sources.js share one source of truth. Collapse duplicate
null/undefined test cases into it.each.

---------

Co-authored-by: aldrinjenson <aldrin@athenaintelligence.ai>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

packages/super-editor/src/core/super-converter/citation-sources.js

@@ -1,5 +1,6 @@
 import { v4 as uuidv4 } from 'uuid';
 import { resolveOpcTargetPath } from './helpers.js';
+import { DEFAULT_XML_DECLARATION } from './constants.js';
 
 export const BIBLIOGRAPHY_NAMESPACE_URI = 'http://schemas.openxmlformats.org/officeDocument/2006/bibliography';
 export const CUSTOM_XML_RELATIONSHIP_TYPE =
@@ -12,14 +13,6 @@ const DEFAULT_SELECTED_STYLE = '/APA.XSL';
 const DEFAULT_STYLE_NAME = 'APA';
 const DEFAULT_VERSION = '6';
 
-const DEFAULT_XML_DECLARATION = Object.freeze({
-  attributes: Object.freeze({
-    version: '1.0',
-    encoding: 'UTF-8',
-    standalone: 'yes',
-  }),
-});
-
 const API_TO_OOXML_SOURCE_TYPE = Object.freeze({
   book: 'Book',
   journalArticle: 'JournalArticle',

packages/super-editor/src/core/super-converter/constants.js

@@ -11,6 +11,15 @@ export const COMMENT_FILE_BASENAMES = [
   'commentsExtensible.xml',
 ];
 
+/** Standard XML declaration used for all OOXML parts */
+export const DEFAULT_XML_DECLARATION = Object.freeze({
+  attributes: Object.freeze({
+    version: '1.0',
+    encoding: 'UTF-8',
+    standalone: 'yes',
+  }),
+});
+
 // Comment-related relationship types (used for pruning stale rels on export)
 export const COMMENT_RELATIONSHIP_TYPES = new Set([
   'http://schemas.openxmlformats.org/officeDocument/2006/relationships/comments',

packages/super-editor/src/core/super-converter/exporter.js

@@ -39,6 +39,7 @@ import { translateVectorShape, translateShapeGroup } from '@converter/v3/handler
 import { translator as wTextTranslator } from '@converter/v3/handlers/w/t';
 import { translator as wFootnoteReferenceTranslator } from './v3/handlers/w/footnoteReference/footnoteReference-translator.js';
 import { carbonCopy } from '@core/utilities/carbonCopy.js';
+import { DEFAULT_XML_DECLARATION } from './constants.js';
 
 const DEFAULT_SECTION_PROPS_TWIPS = Object.freeze({
   pageSize: Object.freeze({ width: '12240', height: '15840' }),
@@ -586,11 +587,7 @@ export class DocxExporter {
 
   #generate_xml_as_list(data, debug = false) {
     const json = JSON.parse(JSON.stringify(data));
-    const declaration = this.converter.declaration?.attributes ?? {
-      version: '1.0',
-      encoding: 'UTF-8',
-      standalone: 'yes',
-    };
+    const declaration = this.converter.declaration?.attributes ?? DEFAULT_XML_DECLARATION.attributes;
     const xmlTag = `<?xml${Object.entries(declaration)
       .map(([key, value]) => ` ${key}="${value}"`)
       .join('')}?>`;

packages/super-editor/src/tests/export/docxExporter.test.js

@@ -41,6 +41,29 @@ describe('DocxExporter', () => {
     expect(xml).toContain('Format=<<NUM>>_<<VER>>');
   });
 
+  it.each([
+    { label: 'null', stub: { declaration: null } },
+    { label: 'undefined', stub: {} },
+  ])('uses default XML declaration when converter.declaration is $label', ({ stub }) => {
+    const exporter = new DocxExporter(stub);
+
+    const data = {
+      name: 'w:document',
+      attributes: {},
+      elements: [
+        {
+          name: 'w:t',
+          elements: [{ type: 'text', text: 'Hello' }],
+        },
+      ],
+    };
+
+    const xml = exporter.schemaToXml(data);
+
+    expect(xml).toContain('<?xml version="1.0" encoding="UTF-8" standalone="yes"?>');
+    expect(xml).toContain('<w:t>Hello</w:t>');
+  });
+
   it('encodes all ampersands in text nodes including entity-like sequences', () => {
     const exporter = new DocxExporter(createConverterStub());