type X = { a: string } | { b: string }

// Works in 4.3.5 and 4.4.2
function func1<T extends X>(value: T) {
  if ('a' in value) {
    const a = value.a
    console.log('a', a)
  } else {
    const b = value.b
    console.log('b', b)
  }
}

// Works in 4.3.5, not in 4.4.2
function func2<T extends X>(value: T) {
  if ('a' in value) {
    const { a } = value // Property 'a' does not exist on type 'X'.(2339)
    console.log('a', a)
  } else {
    const { b } = value // Property 'b' does not exist on type 'X'.(2339)
    console.log('b', b)
  }
}