You can easily test your Coffeescript code with a dynamic type checker and be perfectly type safe, even at runtime! Why for gods sake convert your code base to another language primarily for imaginary type safety?

But for some strange reason entire armies of developers move to Microsoft's Typescript, living their imaginary type save dream. Moving from a language as Coffeecript to Typescript is like dropping at least 25% of your productivity. Not only you'll have to write more code, which in itself increases the chance for bugs, but you'll also be fighting countless compiler issues, installing numerous @types modules, having intellectual discussions about types and whatsoever to make it 'kind of work'. Oh, and almost none of the TS code bases I've seen are without the 'any' keyword, which is actually an instant breach of your type safe haven. IMAO 'any' should never pass a code review in a Typescript project if you want to stay true to your religion. With such a strict regime, like you are forced to with real strictly typed languages, would completely eliminate TS. Without 'any' it's practically impossible to write a large code base with it.

I wrote numerous relatively bug free applications in Coffeescript, small and large as well. Just do good testing and you'll be fine, and as a bonus you'll have type safety at runtime! The mine field is not types IMAO, there is so much more to high quality code bases.