message: Add "Error:" prefix to error messages
diff: @@ -16,7 +16,7 @@ mod installer;
  fn main() {
  setup_panic!();
  if let Err(e) = run() {
  - eprintln!("{}", e);
  + eprintln!("Error: {}", e);
  for cause in e.iter_causes() {
  eprintln!("Caused by: {}", cause);
  }
  