They're trying to do something that's fundamentally very hard. Unifying server-side and client-side code was always going to cause confusion when the difference becomes relevant.
Personally I'd rather go in the direction of having code that's explicitly server-side, explicitly client-side, or explicitly shared utilities. But you'd need more of a type-safe mentality to take that approach, and you'd probably scare off the majority who prefer runtime errors over build-time errors.
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