I think this is a symptom of using weakly typed languages as well. If your argument types are declared to be options/eithers, then you need to handle the empty case, but usually it's easier and better to just move that optional handling further up the callstack or type system.

A lot of `if (input == null)` checks are because you're just not sure whether the argument being passed in will have a value, and it's too much work for your small feature PR to refactor the whole codebase to resolve it.

Use typescript/python-with-mypy/haskell/rust/whatever and this problem mostly disappears.