update sdoc module (#5437)

frontend/src/components/file-content-view/sdoc.js

@@ -1,6 +1,5 @@
 import React from 'react';
 import { SDocViewer } from '@seafile/sdoc-editor';
-import { defaultContentForSDoc } from '../../utils/constants';
 
 import '../../css/sdoc-file-view.css';
 
@@ -9,9 +8,10 @@ const { fileContent } = window.app.pageOptions;
 class FileContent extends React.Component {
 
   render() {
+    const document = fileContent ? JSON.parse(fileContent) : null;
     return (
       <div className="file-view-content flex-1 o-auto sdoc-file-view p-0 d-flex flex-column">
-        <SDocViewer document={fileContent ? JSON.parse(fileContent) : defaultContentForSDoc} config={{}} />
+        <SDocViewer document={document} />
       </div>
     );
   }