how to borrow iterator `items` for distinct type?

[aiac]

    type A = distinct array[4, uint8]
    
    let a: A = cast[A]([uint8 0, 0, 1, 1])
    
    iterator items(a: A): uint8 {.borrow.}
    
    for b in a:
      echo b
    
    
    
    Run
    
    
    /root/.local/share/mise/installs/nim/2.0.2/lib/system/iterators.nim(35, 10) 
Error: internal error: proc has no result symbol
    No stack traceback available
    To create a stacktrace, rerun compilation with './koch temp r <file>', see 
https://nim-lang.github.io/Nim/intern.html#debugging-the-compiler for details
    
    
    Run