Standalone Export has modifiedAt missing, adding modifiedAt to fix it. Thanks to xet7 !

models/wekanCreator.js

@@ -140,6 +140,8 @@ export class WekanCreator {
         isActive: true,
         isCommentOnly: false,
       }],
+      // Standalone Export has modifiedAt missing, adding modifiedAt to fix it
+      modifiedAt: this._now(wekanBoard.modifiedAt),
       permission: wekanBoard.permission,
       slug: getSlug(wekanBoard.title) || 'board',
       stars: 0,