Console error

public class Hangman {

  public static void main(String[] args) {
    // Your incredible code goes here...
    Game game = new Game("treehouse");
    Prompter prompter = new Prompter(game);
    prompter.displayProgress();
    boolean isHit = prompter.promptForGuess();
    if (isHit) {
      System.out.println("We got a hit");
    } else {
      System.out.println("Oops missed!");
    }
    prompter.displayProgress();
  }
}

import java.util.Scanner;

class Prompter {
  private Game game;

  public Prompter(Game game) {
    this.game = game;
  }

  public boolean promptForGuess() {
    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter a Letter: ");
    String guessInput = scanner.nextLine();
    char guess = guessInput.charAt(0);
    return game.applyGuess(guess);
  }

  public void displayProgress() {
    System.out.printf("Try to solve:  %s%n",
                      game.getCurrentProgress());
  }
}

class Game {
  private String answer;
  private String hits;
  private String misses;

  public Game(String answer) {
    this.answer = answer;
  }

  public boolean applyGuess(char letter) {
    boolean isHit = answer.indexOf(letter) != -1;
    if(isHit) {
      hits += letter;
    } else {
      misses += letter;
    }
    return isHit;
  }

  public String getCurrentProgress() {
    String progress = "";
    for (char letter : answer.toCharArray()) {
      char display = '-';
      if (hits.indexOf(letter) != -1 ) {
        display = letter;
      }
      progress += display;
    }
    return progress;
  }

}