And from founding a startup on Scala (Lift + Play), grow over some years and sell, I most dread compiler errors with the type magic. If something doesn't compil

And from founding a startup on Scala (Lift + Play), grow over some years and sell, I most dread compiler errors with the type magic. If something doesn't compile because of types, the error messages (at least some years back) were so confusing, it took quite some time to fix problems.