Why auto doesn't work with void?

[alexeypetrushin]

The code below would fail, I guess because sugar macro can't handle `void` 
return type. [play](https://play.nim-lang.org/#ix=4sst) Is there workaround for 
this?
    
    
    import std/sugar
    
    proc on_click(fn: proc(event: string): void): void =
      discard
    
    on_click((e) => discard)
    
    
    Run