How to suppress "save changes" dialog in jsx script

I have a photoshop jsx script that will work through multiple folders of images to be focus-stacked and output a final stacked image for each.  I want it to run non-interactively after telling it where the images are, as I may need it to crunch away for hours without me babysitting it.  The script is pasted below. 

The problem is that at the end of each stacking operation, a dialog box still appears, asking, Save changes to Adobe Photoshop document "Untitled-1" before closing?  Yes / No / Cancel.   I have included two lines of code that I thought would prevent this, but they don't do so:

app.displayDialogs = DialogModes.NO;
app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);

The last of these two lines is where the prompt arises, and execution halts until I click No. How do I suppress it, have the close() function not save changes as it closes the document, and have the script continue?

I am running Adobe Photoshop 2020 21.2.0 release in Windows 10 Home 10.0.18363.

// auto_focus_stack.jsx
// Adapted from a script by SuperMerlin at 
// https://community.adobe.com/t5/photoshop/automate-focus-stacking-script-action-help-needed/td-p/10483237?page=1
//
// Place this script in the Adobe Photoshop Presets Scripts directory.
//
// To run:  
// * Create a top folder with subfolders inside. 
// * Each subfolder should contain a series of images to stack into a single image and no other files.
// * Name each subfolder by the desired filename of the output stacked image, but omit the file extension.
//   E.g., if the stacked image filename should be "NorthSide.jpg", then name the subfolder "NorthSide".
//   The script will place the stacked images into a new subfolder called "processed" and will add the
//   file extension in the file names.
// * Open Photoshop and start the script with File > Scripts > auto_focus_stack. 
// * Select the top folder. Click Select Folder.
//
// The script will then create a "processed" subfolder, stack the images in each of the other subfolders,
// and save the stacked images in the "processed" subfolder.  

#target photoshop;
app.bringToFront();
app.displayDialogs = DialogModes.NO;
main();

function main(){
  // Asks user to select top directory.
  var selectedFolder = Folder.selectDialog("Please select the top folder to process.");    
  if(selectedFolder == null) return;

  // Gets a list of subfolders and files in the top directory.
  var contents = selectedFolder.getFiles();
  if(contents == null) return;

  // Creates an output subfolder.
  var outFolder = Folder(selectedFolder + "/processed");
  if(!outFolder.exists) outFolder.create();

  // Works on each subfolder, skipping other items in the top folder.
  for(var dir_ind = 0; dir_ind < contents.length; dir_ind++) {
    if(contents[dir_ind] instanceof Folder && contents[dir_ind].name != 'processed') {
	var stackFolder = contents[dir_ind];
        // Gets a list of photo files in the subfolder.
        var pictureFiles = stackFolder.getFiles(/\.(jpg)$/i);
        
        // Does the focus stacking.
        stackFiles(pictureFiles);
        selectAllLayers();
        autoAlign();
        autoBlendLayers();
	
        // Saves the stacked photo after reducing its size.
        resizeLayer(0.5);
        var saveFile = new File(outFolder + '/' + stackFolder.name + '.jpg');
        SaveJPEG(saveFile);

        // Closes the photos that were stacked.
        app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);	
    }
  }

  alert("Script completed.");
};

function resizeLayer(factor) {
  new_width = app.activeDocument.width.value*factor
  new_height = app.activeDocument.height.value*factor
  app.activeDocument.resizeImage(new_width, new_height);
}

function autoBlendLayers(){
var d=new ActionDescriptor();
d.putEnumerated(stringIDToTypeID("apply"), stringIDToTypeID("autoBlendType"), stringIDToTypeID("maxDOF"));
d.putBoolean(stringIDToTypeID("colorCorrection"), true);
d.putBoolean(stringIDToTypeID("autoTransparencyFill"), true);
executeAction(stringIDToTypeID("mergeAlignedLayers"), d, DialogModes.NO);
};

function SaveJPEG(saveFile){
  SaveOptions = new JPEGSaveOptions(); 
  SaveOptions.embedColorProfile = true; 
  SaveOptions.formatOptions = FormatOptions.STANDARDBASELINE
  SaveOptions.quality = 12;
  activeDocument.saveAs(saveFile, SaveOptions, true, Extension.LOWERCASE); 
};

function SaveTIFF(saveFile){
tiffSaveOptions = new TiffSaveOptions(); 
tiffSaveOptions.embedColorProfile = true; 
tiffSaveOptions.alphaChannels = true; 
tiffSaveOptions.layers = true;
tiffSaveOptions.imageCompression = TIFFEncoding.TIFFLZW; 
activeDocument.saveAs(saveFile, tiffSaveOptions, true, Extension.LOWERCASE); 
};

function selectAllLayers() {
var desc = new ActionDescriptor();
var ref = new ActionReference();
ref.putEnumerated( charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') );
desc.putReference( charIDToTypeID('null'), ref );
executeAction( stringIDToTypeID('selectAllLayers'), desc, DialogModes.NO );
};

function stackFiles(sFiles){  
var loadLayersFromScript = true;  
var SCRIPTS_FOLDER =  decodeURI(app.path + '/' + localize('$$$/ScriptingSupport/InstalledScripts=Presets/Scripts')); 
$.evalFile( new File(SCRIPTS_FOLDER +  '/Load Files into Stack.jsx'));   
loadLayers.intoStack(sFiles);  
};

function autoAlign() {
var desc = new ActionDescriptor();
var ref = new ActionReference();
ref.putEnumerated( charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') );
desc.putReference( charIDToTypeID('null'), ref );
desc.putEnumerated( charIDToTypeID('Usng'), charIDToTypeID('ADSt'), stringIDToTypeID('ADSContent') );
desc.putEnumerated( charIDToTypeID('Aply'), stringIDToTypeID('projection'), charIDToTypeID('Auto') );
desc.putBoolean( stringIDToTypeID('vignette'), false );
desc.putBoolean( stringIDToTypeID('radialDistort'), false );
executeAction( charIDToTypeID('Algn'), desc, DialogModes.NO );
};

function autoBlend() {
var desc = new ActionDescriptor();
desc.putEnumerated( charIDToTypeID('Aply'), stringIDToTypeID('autoBlendType'), stringIDToTypeID('maxDOF') );
desc.putBoolean( charIDToTypeID('ClrC'), true );
executeAction( stringIDToTypeID('mergeAlignedLayers'), desc, DialogModes.NO );
};