how to clear clipboard

app.executeMenuCommand('copy') also crashes on Mac.

I use a series of script/macros to copy-and-paste elements from "Layout" templates to "Tray" templates, in preparation for lasering. On very rare occasions there is NOTHING in the "Layout" template so the correlating "Tray" position should be left blank. The problem is, since there is still residual content in the clipboard it is pasted into the "Tray" template in the space that should be left blank. I thought purging the clipboard might fix that problem.

Here is the actual script used for capturing the "Layout" artwork. I've commented out the portion that crashes AI.

//~ Test for text objects then copy content.
testForText();
function testForText() {
  var doc = app.activeDocument;
  app.executeMenuCommand("selectall");
  var sel = doc.selection;
  if (sel.length == 0) {
    alert("There's nothing selected");
//~      app.copy();
//~      aDoc.close(SaveOptions.DONOTSAVECHANGES);
  } else {
    var textFrameDetected = false;
    for (var i = 0; i < doc.selection.length; i++) {
      if (doc.selection.typename == "TextFrame") {
        textFrameDetected = true;
      }
    }
    if (textFrameDetected) {
      alert("A text frame was detected! Release the hounds!");
    } else {
      app.copy();
      aDoc.close(SaveOptions.DONOTSAVECHANGES);
    }
  }
 !}

Yes, I could use Keyboard Maestro to purge the system clipboard. It would just mean breaking the script into two scripts (I think).

You've caused me to think, maybe I could just copy a temporary object to the clipboard, in the event the selection is blank, then delete said object in the "Tray" template. Seems tedious for something that may occur once a year.

By the way, thanks to Silly-V​ for the "Test for Text" snippet!