False positive "Capture parameter count does not match () => Unit vs. () => Unit / { Foo }" when passing `box {}` to generic function

```effekt
interface Foo {}
def bar[C](b: C) = ()

def main() = {
bar[=> Unit / Foo at {}](box{})
}
```
Note that this works:
```effekt
interface Foo {}
def bar(b: => Unit / Foo at {}) = ()

def main() = {
bar(box{})
}
```
but this doesn't:
```effekt
interface Foo {}
def bar(b: => Unit / Foo at {}) = ()

def main() = {
val a = box {}
bar(a)
}
```
The best solution would be to just make all examples compile, meaning that `=> Unit at {}` is a subtype of `=> Unit / {...} at {}`, and similarly for all functions.