The trick is not to create reliable software. The trick is to create systems that can tolerate complete failure of the software. This is the secret to airplane reliability.

(Although they still do their best to make the software reliable, they do not bet lives on its reliability.)

Safe Systems from Unreliable Parts https://www.digitalmars.com/articles/b39.html

Designing Safe Software Systems part 2 https://www.digitalmars.com/articles/b40.html