Function check_start 

pub fn check_start(
    options: &[GameOption],
    start: &[GameArg],
) -> Result<(), String>

Checks that the start options start are ones the game offers (options): each names one, has a value if it takes one and has none if it takes none. Every operation that starts the game calls it first, whether the options came from the command line or from JSON.

Errors

What is wrong with the first option that is not right.