> since I don't throw errors very often

I call shenanigans. Maybe you don't intentionally throw exceptions very often, but that's hardly the point of exceptions.

Javascript is an interpreted language. Everything is an exception. Do you ever fat-finger a function name during development? That's an exception. Ever accidentally try to use "this" when it's pointing at "window"? Exception.

Those simple, natural mistakes can be lurking anywhere. They're far easier to detect and correct when the failure is propagated backward correctly to the right callers.