Bug? Edge on iOS always throws error when a global error handler is attached.

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Occasional Visitor

When I have a global event handler attached to the main frame, Edge on iOS always seems to throw an error and the event.error object is always NULL. Is this by design?

 

<!doctype HTML>
<html>
<head>
  <title>Global error handler test</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
  <script type='text/javascript'>
    window.addEventListener('error', function(event) {
      alert(event.message + " - " + event.error);
    });
  </script>
</body>
</html>

 

When viewed in Edge iOS, this will always show an alert showing "Script error. -  null". If I intentionally throw an error after adding the handler, then I first get an alert for it with the expected message, but then I also get the generic null error message too.

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