trying to create a "NoUI" document and export as SVG like this:

opendoc = app.documents.addDocumentNoUI();
opendoc.exportFile(file, ExportType.SVG);

I get the attached error in AI

I can't think of any other way to export an SVG via script. Obviously there are scripting things that don't work with NoUI documents, but it seems like this one should. Am I doing something wrong?