ExtendScript Photoshop Edit Contents Smart Layer

I have now tested with CS6,  CC 2014, CC 2018, CC 2019, PS 2020 and PS 2021.  All seen to fail to open the Smart Object Layer's  object that your Mac created right away like the one I had downloaded.  Where in PS 2021 version 22.1 if I  wait using a wait till message the object will open.   In prior Photoshop the object never opens I have to add the open for the temp work file that was created by Photoshop for placeLeyerEditContents  but did not open.  

So the scripts in my toolkit work in Photoshop version prior to PS 2021 on windows machines.  I'm not positive they will on Mac for I'm not sure of where Photoshop created the temp work file on a mac.  This is what I use for Windows it may be the same for  Mac. depends on Forder.temp beint the place the file is created

var workFile = new File(Folder.temp + "/" +  name);  // May work for both Windows and Mac

PS 22.1 can occasionally have problem if I add the Open Command. However,  adding the open performs faster than waiting for the object to eventually open So I will not be changing my scripts for waiting requires human interaction which is not appropriate for a batch process.

I look at you script its seem to work on my machine but has issues with Place scaling images  and it  leave the object open.   I particularly do not like templates that have smart object  layer where the object is layered and to populate  the template you have to edits late within the object. Templates like that are too hard to use and  requite a custom script for automation.  It is far easier to create templates that simply need the smart object replaced.  So I simplified your Template or the one you purchased or downloaded.   I rasterized some layers  and moved the tool bar layers into the template from the object and added a camera layer.  This template can be batch processed with my script and if you use its edit option replacement images can be any size. The phone screen will be filled with image content.  If replacement images  are Phone size my scripts default isuse  Replace content not edit here the template. samsung-s20-mockup-xxx.psd 

http://www.mouseprints.net/old/dpr/samsung-s20-mockup-xxx.psd 

app.runMenuItem(stringIDToTypeID('placedLayerEditContents'));

if (objectIsPsObject(activeDocument.activeLayer)) app.runMenuItem(stringIDToTypeID('placedLayerEditContents'));
else alert(activeDocument.activeLayer.name + " Object can not be edited using Photoshop its unchanged.");

We all make mistakes and I did forget to paste the inner function smartobject_file_ext. So you were right when you posted the code I posted does not work.  So here is a  script your one line script to open Photoshop active layers smart object layer object in  Photoshop for editing. The code to edit the object is not included. However. That code should end with a Close that Saves the edits. So the opened work file will  closed out of Photoshop so the active document will become the original current document  Its Active Smart object layer's  object will be updated and new pixels rendered for the layers content.  As the Script stands there will be at least two open documents in Photoshop when it ends. The original document you ran the script from and the opened temp work document. Should] the object be a Photoshop object.

if (!documents.length) alert('There are no documents open.', 'No Document');
else {
   if (app.activeDocument.activeLayer.kind!=LayerKind.SMARTOBJECT) alert("ActiveLayer not Smart Object Layer");
   else {
      if (!objectIsPsObject(activeDocument.activeLayer)) alert(activeDocument.activeLayer.name + " Object can not be edited using Photoshop its unchanged.");
      else app.runMenuItem(stringIDToTypeID('placedLayerEditContents'));
      // Add code here to edit the smart object temp work file

     // Close the work file with save to clost the temp wok file out of Phtoshop and have Photoshop updater the orifinals smart object layers objeyy
   }
}

function objectIsPsObject(SOlayer) {
	//Thanks to r-bin
	var ext = smartobject_file_ext(SOlayer);  
    var rc = true;
	switch (ext)  
		{  
		case "nef":  
		case "cr2":  
		case "crw":  
		case "raf":  
		case "orf":  
		case "mrw":  
		case "dcr":  
		case "mos":  
		case "raw":  
		case "pef":  
		case "srf":  
		case "dng":  
		case "x3f":  
		case "erf":  
		case "sr2":  
		case "kdc":  
		case "mfw":  
		case "mef":  
		case "arw":  
		case "nrw":  
		case "rw2":  
		case "rwl":  
		case "iiq":  
		case "3fr":  
		case "fff":  
		case "srw":  
		case "ai":
		case "svg":
		case "pdf":
		case "esp":
			rc = false.	
			break;  
		case "error":  
			rc = false;
			break;         
  		default:  
			rc = true;
			break;  
    }  
	return rc;
}

function smartobject_file_ext(layer) {  
    try {         
        var r = new ActionReference();     
        r.putProperty(stringIDToTypeID("property"), stringIDToTypeID("smartObject"));  
        r.putIdentifier(stringIDToTypeID("layer"), 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) { return "error"; }  
}