Handling Type Inference for Nullable Values in TypeScript Effects

Is there a way to avoid this problem other than just casting the final value as

string | null

string | null

const getFoo = Effect.gen(function*() {
  let foo: string | null = null

  yield* Effect.sync(function() {
    foo = "Hello!"
  })

  return foo
})

const getFoo = Effect.gen(function*() {
  let foo: string | null = null

  yield* Effect.sync(function() {
    foo = "Hello!"
  })

  return foo
})

The problem is that

getFoo

getFoo

's type is

Effect.Effect<null>

Effect.Effect<null>

, not

Effect.Effect<string|null>

Effect.Effect<string|null>