Re: mumbo jumbo
When I was writing operating systems I realized that there were no errors. If a file can't be opened, read etc. the operating system just has to deal with it just as it has to deal with a successful file read.
At Xerox, the copy machine software for a large copier was about 80% dealing with error conditions (jammed paper, out of paper etc.). A language that assumes the "main line" is important and has a special exception mechanism for errors, in my opinion, is broken. Error recovery is hard and the language should support it well over making the "main line" easy to code.
Extensive testing of error conditions is hard but absolutely necessary.