Code crashes without any concrete error and no help documents #928

 [Verb("add", HelpText = "Add file contents to the index.")]
    class AddOptions {
        //normal options here
    }
    [Verb("commit", HelpText = "Record changes to the repository.")]
    class CommitOptions {
        //commit options here
    }
    [Verb("clone", HelpText = "Clone a repository into a new directory.")]
    class CloneOptions {
        //clone options here
    }

    static int Main(string[] args) {
        return CommandLine.Parser.Default.ParseArguments<AddOptions, CommitOptions, CloneOptions>(args)
            .MapResult(
                (AddOptions opts) => RunAddAndReturnExitCode(opts),
                (CommitOptions opts) => RunCommitAndReturnExitCode(opts),
                (CloneOptions opts) => RunCloneAndReturnExitCode(opts),
                errs => 1);
    }

    private static int RunCloneAndReturnExitCode(CloneOptions opts)
    {
        return 1;
    }

    private static int RunCommitAndReturnExitCode(CommitOptions opts)
    {
        return 1;
    }

    private static int RunAddAndReturnExitCode(AddOptions opts)
    {
        return 0;
    }
}