How to alter an Exception message.

alter_exception_message.php

<?php
$augmented_message = $exception->getMessage() . "\nMy augementation";
$reflected_exception = new \ReflectionObject($exception);
$message_property = $reflected_exception->getProperty('message');
$message_property->setAccessible(TRUE);
$message_property->setValue($exception, $augmented_message);
throw $exception;