Script to extract a list of all spelling errors in a document?

Here's a script that collects all words caught by the spell checker and places them in a new document.  It's a horrible thing, very slow, and  right up there in the top-10 of ugly solutions. But it works. It came out of a discussion a few years ago here

https://community.adobe.com/t5/indesign/how-to-compare-a-word-with-indesign-user-dictionary-words/m-p/10450665?page=1

which petered out after a few exchanges.

(function () {
  
  const props = app.spellPreferences.properties;
  const spellWindow = app.menuActions.item ('$ID/Check Spelling...');
  
  var typos = [];
  var knownTypo = {};
  
  function record (typo) {
    if (!knownTypo[typo]) {
      knownTypo[typo] = true;
      typos.push (typo);
    }
  }

  // Begin ----------------------------------------------
  
  // Hide the layout window to speed things up
  app.windows[0].minimize();
  
  app.spellPreferences.properties = {
    checkCapitalizedSentences: false,
    checkCapitalizedWords: false,
    checkRepeatedWords: false,
    checkMisspelledWords: true
  }

  spellWindow.invoke();
  if (!app.selection.length) { // No spelling errors, nothing to do
    exit();
  }

  // If there's a typo, it's now selected
  record (app.selection[0].contents);
  
  var i = app.selection[0].index; // The location of the typo
  spellWindow.invoke();
  while (app.selection[0].index !== i) { // Stop when we catch the same word
    i = app.selection[0].index;
    record (app.selection[0].contents);
    spellWindow.invoke(); // Go to the next typo
  }
  app.selection = null;
  
  // Restore the layout window and the spell preferences
  app.activate();
  app.spellPreferences.properties = props;
  
  // Create a new document and add the typos.
  app.documents.add().textFrames.add ({
    geometricBounds: app.documents[0].pages[0].bounds,
    contents: typos.sort().join('\r'),
  });
  
}());