I'm getting the impression that TS is avoiding making too many dramatic changes to JS. Functions that return undefined in vanilla JS would suddenly return whatever happened to be the last statement; likely leading to unexpected behavior.
i wonder how hard it would be for their compiler to catch the opposite case, then - a program using the return value of a function without a return statement. i think that was my most common bug when i was doing javascript programming, because all the other languages i was using at the time had implicit returns.
