4 ms·

I just tried it in the online playground. I didn't get any sort of error with one of the cases unhandled. https://www.typescriptlang.org/play/?noFallthroughCase

• yen223 2y ago
  Hmm. I think this is because in that situation, all cases (including the unhandled one) are "correctly" returning undefined. I can see that if I made the branch return a string, Typescript will correctly show the "Not all code paths return a value" error
  • DylanSp 2y ago
    Yep, or if you declare an explicit return type for the function, TS correctly gives a "Function lacks ending return statement and return type does not include 'undefined'." error. But if you have a function that's purely side-effecting, I think you still have to do something manual.