message: Use eprintln! instead of println! for errors
diff: @@ -97,7 +97,7 @@ fn run(options: Run) {
  match execute_wasm(&options) {
  Ok(()) => {}
  Err(message) => {
  - println!("{:?}", message);
  + eprintln!("{:?}", message);
  exit(1);
  }
  }
  