goto without fallthrough?
=========================

A missing return/break/goto/etc can easilly cause incorrect behavior:

    func f() -> bool
    {
        do_stuff()
      err:                      #<--- missing "return true" before this line
        handle_error()
        return false
    }

Solution 1:

  err:            #<--- fall-through not allowed (except if first in a block)
    
    fallthrough
  err:            #<--- fall-through allowed

    unreachable
  err:            #<--- fall-through not possible