That's great! Though, by making it not forced and giving users a choice, you never know which library code you call might not use those features and still panic

That's great! Though, by making it not forced and giving users a choice, you never know which library code you call might not use those features and still panic when you use it. (Just to be clear, I don't really propose that a language should offer only panic-free operations; I just think it's a nice thought experiment and discussion to have).