"human programmers forget to account for edge cases"

Which is precisely the rationale which led to Standard Operating Procedures and Best Practices (much like any other Sector of business has developed).

I submit to you, respectfully, that a corporation shall never rise to a $75 Billion Market Cap without a bullet-proof adherence to such, and thus, this "event" should be properly characterized and viewed as a very suspicious anomaly, at the least

https://news.ycombinator.com/item?id=41023539 fleshes out the proper context.