TypeScript Version: 2.2.0-dev.20161122

With --strictNullChecks.

Code

function spread(arg?: {}): {} {
  return {...arg}
}
spread()

Expected behavior:

spread() returns empty object {}.

Actual behavior:

Spread types may only be created from object types.

The spec specifically allows null and undefined spread arguments by having an early check before the ToObject abstract operation (3.1.2).