In a new post to his site Free Litjen talks about defensive programming and the part that sane default handling plays when dealing with exceptions that might pop up.
With over half a million visitors a week and lots of scrapers, bots and other stuff visiting, these exceptions and fatal errors clog up logging quite a bit. Not to the point that we can't handle the volume, but it generates false positives in monitoring channels and it is something we do not want to act upon anyway.
So while I'm happy to see some defensive programming I would be even happier if exceptional situations would be silently resolved to default situations.
The post starts with a quote about defensive programming and how, despite it not being an ideal use, many applications had been seen using exceptions to handle errors and messaging. He proposes another methodology where a set of default values are used instead of just failing on any error hit with the input. The idea has merit but it can also lead to other frustrations like hidden errors in testing and situations where an exception makes more sense than a default.