Text Replace ( i am getting error while replace Envelope Text ) Can anyone help me

var active_doc = app.activeDocument;
var dlg = new Window('dialog', 'TEXT REPLACE');
    var gro =dlg.add('group');
    gro.orientation = 'row';
       
    var Orderno = gro.add('StaticText' ,{x:10,y:40,width:70,height:20});
    Orderno.text = 'TEXT :';
    var OrdernoValue = gro.add('EditText',{x:10,y:40,width:100,height:20},"");
    OrdernoValue.text   = OrdernoValue.value;
     
    var g_btn = dlg.add("group"); 
    var btn_ok = g_btn.add("button", undefined, "Ok"); 
    var btn_ccl = g_btn.add("button", undefined, "Cancel");
    btn_ok.onClick = function()
    { 
        if(Orderno)
        {
            dlg.close();
        }
        else
        {
            return;
         }
     }
dlg.show();
replace(/TEXT/gi,OrdernoValue.text);


function replace(search_string,replace_string)
{
var text_frames = active_doc.textFrames; 

if (text_frames.length > 0) 
{ 
    for (var i = 0 ; i < text_frames.length; i++) 
      { 
          var this_text_frame = text_frames; 
         
           var new_string = this_text_frame.contents.replace(search_string, replace_string); 
            
           if (new_string != this_text_frame.contents) 
               { 
                    this_text_frame.contents = new_string; 
               } 
      } 
} 
}