private async Task <Validation <BaseError, Unit> > Validate(UpdateFFmpegSettings request) => (await FFmpegMustExist(request), await FFprobeMustExist(request))
public Task <Either <BaseError, Unit> > Handle( UpdateFFmpegSettings request, CancellationToken cancellationToken) => Validate(request) .MapT(_ => ApplyUpdate(request)) .Bind(v => v.ToEitherAsync());