New control flow analysis improvements in typescript are quite mind blowing...

controlflow.ts

type MyObject = { a: 1; b: 2; c: 3 } | { a: 4; b: 5; c: 6 } | { a: 7; b: 8; c: 9 };
declare const object: MyObject;
const { a, b, c } = object;

if (a === 1) {
  console.log(object); // type is {a: 1, b: 2, c: 3} (since 4.4)
} else if (a === 2) {
  // TS2367: This condition will always return 'false' since the types '4 | 7' and '2' have no overlap.
  console.log(object); // type inferred as never
} else if (b === 5) {
  console.log(object); // type inferred {a: 4, b: 5, c: 6} (since 4.4)
  console.log(a); // type inferred as 1 (will be in 4.6)
  console.log(c); // type inferred as 3 (will be in 4.6)
} else if (c === 9) {
  console.log(object); // type inferred as {a: 7, b: 8, c: 9}
  console.log([a, b]); // type inferred as the tuple [7, 9] (will be in 4.6)
} else {
  console.log(object); // type inferred as never
}