FFMpeg Convert file to mkv and subs to srt

/**
 * Requires FFMpeg to be configured
 * @author jbiancam1
 * @output Sub Converted stream file created
 */
function Script(SubType)
{
    const subType = 'srt';

    Logger.ILog('Sub Type: ' + subType);

    let output = Flow.TempPath + '/' + Flow.NewGuid() + ".mkv";

    Logger.ILog('Output: ' + output);

    let fFMpeg = Flow.GetToolPath('FFMpeg');
    let original = Variables?.file?.FullName;
    let execArguments = ["-i", original, "-c", "copy", "-map", "0", "-c:s", subType, output];

    Logger.ILog('Original file: ' + original);
    Logger.ILog('Arg List: ' + execArguments.toString());

    let process = Flow.Execute({
        command: fFMpeg,
        argumentList: execArguments
    });

    if(process.exitCode !== 0){
        Logger.ELog('Failed to convert subs: ' + process.exitCode);
        return -1;
    }

    Flow.SetWorkingFile(output);
    Logger.ILog('Set ' + output + 'to WorkingFile.');

    return 1;
}