I use Ocaml and the type system and language server basically remove the need for things like a debugger, or even run-time testing while developing, that you might need in some other language. It tells you type of every function, variable, etc. While it's not needed, the language server works in tandem with the type system to basically tell you exactly what's happening in your code.
Type systems are half of the equation, but what do you do when the algorithm is wrong? Type systems don't constrain you from writing incorrect solutions to the echo cancelation problem...you need real world data and runtime tooling for that. This is where IDE type tooling shines, nobody cares about the editor or the code in the end...
