I agree. I've worked in both Elm and ClojureScript. In one, I have to constantly deal with compiler errors. In the other, about as much runtime errors. The net time for error handling is the same. But the net time in actually writing code is in favor of ClojureScript, which requires at least half as many lines as Elm (and often much less than half).
Error handling is somewhat over-emphasized in comparison to other things that affect productivity (and maintainability).
Especially on the JVM where most exceptions need to be explicitly handled and the ones that aren't can be handled in a way that doesn't impact users.
I think they are over-estimating how much people care about runtime errors.