Remove DocumentAncestors recursively for all SmartObjects in a PSD

I am currently working on a script that can clean the DocumentAncestors in a .psd file. 

Since there are SmartObjects in the SmartObjects of the PSD, I am current trying to recursively iterate trough all layers, check if a layer is a SmartObject and if so, iterate into it and check if any further SmartObjects exist. If no more SmartObjects exist, the script starts to delete the DocumentAncestors recursively. 

The problems:

- it seems to iterate correctly through all the layers, but the removal not always seems to work, since there are many DocumentAncestor entries left in the PSD afterwards

- the procedure is also very heavy on the woking volumes. I am currently trying to remove the Ancestors of a 800MB PSD and the working volumes need >150GB of space

- after about 5-10 min, the variable which holds the current SmartObject becomes invalid

The code implements several different little scripts and parts of users found on here (JJMack, Kukurykus just to name a few)

#target photoshop
var count = 0;
const doneIDs = [];
var doc = app.activeDocument;
doc.suspendHistory("Delete Ancestors Metadata", "processSOLayers(doc)");

function processSOLayers(theParent) 
{
    $.writeln("Entering Parent: " + theParent.name );
    count++;
    $.writeln( "Depth: " + count);

    for (var m = 0; m <  theParent.layers.length; m++) 
    {
        var theLayer = theParent.layers[m];

        if (theLayer.typename === "ArtLayer") 
        {
            if (theLayer.kind === LayerKind.SMARTOBJECT) 
            {
                var theVisibility = theLayer.visible;
                app.activeDocument.activeLayer = theLayer;

                var layerID = getLayerId();
                if( layerIsPsObject(layerID) )
                {
                    $.writeln("Opening SmartObject: " + theLayer.name);
                    var smartObject = openSmartObject(theLayer);
                    if( smartObject.id !== theParent.id && !isAlreadyDone(smartObject.id))
                    {
                        processSOLayers(smartObject);
                        deleteDocAncestors(smartObject);
                        smartObject.close(SaveOptions.SAVECHANGES);
                        $.writeln("Saved SmartObject: " + theLayer.name + " ID: " + theLayer.id);
                    }
                    else
                    {
                        smartObject.close(SaveOptions.DONOTSAVECHANGES);
                    }
                }
                theLayer.visible = theVisibility;
            }
            //alert("SO doc cleaned");
        } 
        else
        { 
            //Layerset
            processSOLayers(theLayer);
            $.writeln("Exiting LayerSet: " + theLayer.name );
        }
    }
    
    $.writeln("Exiting parent: " + theParent.name );
    count--;
    $.writeln( "Depth: " + count);
    return;
}

deleteDocAncestors(doc);
//alert("Parent doc cleaned");

function deleteDocAncestors(document) 
{
    if (ExternalObject.AdobeXMPScript === undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
    var xmp = new XMPMeta(document.xmpMetadata.rawData);
    xmp.deleteProperty(XMPConst.NS_PHOTOSHOP, "DocumentAncestors");
    document.xmpMetadata.rawData = xmp.serialize();
    $.writeln("Cleaned Ancestors...")
}

function isAlreadyDone(id)
{
    for( var i = 0; i < doneIDs.length; ++i)
    {
        if( doneIDs[i] === id)
            return true;
    }

    doneIDs.push(id);
    return false;
}

function getLayerId()
{
    var ref = new ActionReference();
    ref.putEnumerated(charIDToTypeID('Lyr '), charIDToTypeID('Ordn'), charIDToTypeID('Trgt')); // reference is active layer
    var layerDesc = executeActionGet(ref);
    var layerID = layerDesc.getInteger(stringIDToTypeID('layerID'));

    return layerID;
}

function openSmartObject (theLayer) 
{
    try
    {
        var idplacedLayerEditContents = stringIDToTypeID( "placedLayerEditContents" );
        var desc2 = new ActionDescriptor();
        executeAction( idplacedLayerEditContents, desc2, DialogModes.NO );

        return app.activeDocument;
    }
    catch(e)
    {
        alert(e.name + " " + e.message);
        return undefined;
    }
};

function smartobject_file_ext(id) 
{  
    try 
    {         
        var r = new ActionReference();     
        r.putProperty(stringIDToTypeID("property"), stringIDToTypeID("smartObject"));  
        r.putIdentifier(stringIDToTypeID("layer"), id);  
        var name = executeActionGet(r).getObjectValue(stringIDToTypeID("smartObject")).getString(stringIDToTypeID("fileReference"));         
         
        var n = name.lastIndexOf(".");
        if (n < 0) return "";
     
        return name.substr(n+1).toLowerCase();  
    }  
    catch (e) 
    {
        $.writeln(e);
        return "error"; 
    }  
}   

function layerIsPsObject(layerID) 
{
	var ext = smartobject_file_ext(layerID);  
	switch (ext)  
		{  
        case "psb":
        case "psd":
            return true;
  		default:  
			return false;
    }  
}