How to get postscript font name for text with paragraph or character styles applied

Would it be possible to change the approach and get the PostScript names of the fonts defined for all paragraph and character styles in the document?

That is, even if those are not actually applied to the text layer.

The DOM is apparently buggy.

With this code you get different results depending on whether a paragraph style is applied. With a style, the DOM code returns an incorrect result. Without a style, the correct font is returned.

var a = app.activeDocument.activeLayer.textItem.font;
var b = app.fonts.getByName(a);
Window.alert(a + ' ' + b.postScriptName);

// thanks to mike hale and paul riggott;
// 2015, use it at your own risk;
if (app.documents.length > 0) {
var myDocument = app.activeDocument;
var theFonts = selectedLayersFonts ();
alert ("the result:"+"\n"+theFonts.join("\n"))
};
////////////////////////////////////
function selectedLayersFonts () {
var theFonts = new Array;
////////////////////////////////////
var selectedLayers = new Array; 
var ref = new ActionReference(); 
ref.putEnumerated( charIDToTypeID("Dcmn"), charIDToTypeID("Ordn"), charIDToTypeID("Trgt") ); 
var desc = executeActionGet(ref); 
if( desc.hasKey( stringIDToTypeID( 'targetLayers' ) ) ){ 
 desc = desc.getList( stringIDToTypeID( 'targetLayers' )); 
  var c = desc.count 
  var selectedLayers = new Array(); 
  for(var i=0;i<c;i++){ 
	try{ 
	   activeDocument.backgroundLayer; 
	   selectedLayers.push(  desc.getReference( i ).getIndex() ); 
	}catch(e){ 
	   selectedLayers.push(  desc.getReference( i ).getIndex()+1 ); 
	} 
  } 
}else{ 
 var ref = new ActionReference(); 
 ref.putProperty( charIDToTypeID("Prpr") , charIDToTypeID( "ItmI" )); 
 ref.putEnumerated( charIDToTypeID("Lyr "), charIDToTypeID("Ordn"), charIDToTypeID("Trgt") ); 
 try{
	activeDocument.backgroundLayer;
	selectedLayers.push( executeActionGet(ref).getInteger(charIDToTypeID( "ItmI" ))-1);
 }catch(e){
	selectedLayers.push( executeActionGet(ref).getInteger(charIDToTypeID( "ItmI" )));
 }
};
////////////////////////////////////
var theNumber = selectedLayers.length;
////////////////////////////////////
for (var m = theNumber; m >= 0; m--) {
try {
var ref = new ActionReference();
ref.putIndex( charIDToTypeID( "Lyr " ), selectedLayers[m]);
var layerDesc = executeActionGet(ref);
var layerSet = typeIDToStringID(layerDesc.getEnumerationValue(stringIDToTypeID("layerSection")));
var isBackground = layerDesc.getBoolean(stringIDToTypeID("background"));
var theName = layerDesc.getString(stringIDToTypeID('name'));
// if not layer group collect values;
if (layerSet != "layerSectionEnd" && layerSet != "layerSectionStart" && isBackground != true) {
var hasText = layerDesc.hasKey(stringIDToTypeID("textKey"));
if (hasText == true) {
var textDesc = layerDesc.getObjectValue(stringIDToTypeID('textKey'));
//checkDesc2 (textDesc)
var paragraphRangeList = textDesc.getList(stringIDToTypeID('paragraphStyleRange'));
var kernRange = textDesc.getList(stringIDToTypeID('kerningRange'));
var rangeList = textDesc.getList(stringIDToTypeID('textStyleRange'));
for (var o = 0; o < rangeList.count; o++) {
var styleDesc = rangeList.getObjectValue(o).getObjectValue(stringIDToTypeID('textStyle'));
//checkDesc2 (styleDesc)
var theSize = styleDesc.getUnitDoubleValue(stringIDToTypeID('size'));
// check for default font;
if (styleDesc.hasKey(stringIDToTypeID('fontPostScriptName')) == true) {var aFont = styleDesc.getString(stringIDToTypeID('fontPostScriptName'))}
else {
	var theDefault = styleDesc.getObjectValue(stringIDToTypeID('baseParentStyle'));
	var aFont = theDefault.getString(stringIDToTypeID('fontPostScriptName'));
	};
theFonts.push([aFont, theSize])
}
}
}
} catch (e) {};
}
return theFonts
};