can't send POD types without `=destroy` warning?

The compiler currently implicitly suggests I should box all my sends of POD types with objects so I can create null destructors (discard), which feels unnecessary. Isn't it isolated by definition?

```nim
var input = newChan[int]()
input.send(1) # isolation.nim(29, 13) Warning: `=destroy`(dest.value) can raise an unlisted exception: Exception [Effect]
```