[Type Error] Null | Type must be cast after a conditional return

[willemneal]

Here is the working example: https://webassembly.studio/?f=zi21djvj57

Consider this example

function orNull(i: i32): Foo | null {
  if (i % 2 == 0)
  return null;
  return new Foo();
}

function example(): Foo | null {
  let x: Foo | null = orNull(1);
  if (x == null){
    return null;
  }
  return id(x); // x is not null, but compiler requires an explicit cast.
}

function id(f: Foo): Foo{
  return f;
}

Not sure how big of a problem this is since it might be better to enforce being explicit, but I thought I'd share it. Also the same is true for if/else branches.

[dcodeIO]

Closing this issue as part of 2020 vacuum because this seems to be fixed meanwhile by extending null checks, at least when using ===, with everything further being tracked in the respective issues dealing with changing the semantics of triple equals.