From Xojo Documentation
If the appropriate Exception statement is missing, the runtime exception error triggers this event and allows you to handle exceptions here.
Returns a Boolean. If it returns True, the standard alert indicating an unhandled exception and quit behavior are suppressed. Return False to allow the default unhandled exception error processing to occur.
The standard behavior is to display a dialog indicating an error occurred. The dialog has a place for the user to enter additional information an optionally click "Send" with the information.
Session is not available from this event handler.