message: Fix assertion when printing bytecode
diff: @@ -67,14 +67,15 @@ pub(crate) struct BcCallArgsFull<S: ArgSymbol> {
  /// Positional-only call arguments, from stack.
  #[derive(Debug)]
  pub(crate) struct BcCallArgsPos {
  - /// Number of positional arguments.
  + /// Range of positional arguments.
  pub(crate) pos: BcSlotRange,
  }
  impl<S: ArgSymbol> BcCallArgsFull<S> {
  + /// Number of positional arguments.
  fn pos(&self) -> u32 {
  - assert!(self.pos_named.start.0 as usize >= self.names.len());
  - self.pos_named.start.0 - (self.names.len() as u32)
  + assert!(self.pos_named.len() >= (self.names.len() as u32));
  + self.pos_named.len() - (self.names.len() as u32)
  }
  }
  