I get an exception if I enter a non-number into the "Please enter 1, 2, or 3" field

```
Please enter 1, 2, or 3
1- New Game
2- Load Game
3- Exit
aa
Traceback (most recent call last):
  File "main.py", line 258, in <module>
    main()
  File "main.py", line 220, in main
    start_choice = int(input())
ValueError: invalid literal for int() with base 10: 'aa'


** Process exited - Return Code: 1 **
```