MainFoo.hx:6: characters 18-21 : Field foo has different type than in Foo
MainFoo.hx:2: characters 11-14 : ... Interface field is defined here
MainFoo.hx:6: characters 18-21 : ... error: Null<Unknown<0>> should be foo.T
MainFoo.hx:6: characters 18-21 : ... have: (...) -> Null<Unknown<0>>
MainFoo.hx:6: characters 18-21 : ... want: (...) -> foo.T