This is also like Null Object or Special Case pattern. It simplifies error handling, and because error handling code is often poorly tested it ends up being a b

This is also like Null Object or Special Case pattern. It simplifies error handling, and because error handling code is often poorly tested it ends up being a big source of catastrophic failures. Making illegal states unrepresentable, or as John Ousterhout puts it: define errors out of existence: https://wiki.tcl-lang.org/page/Define+Errors+Out+of+Existence https://wiki.tcl-lang.org/page/Define+Errors+Out+of+Existenc...