running tool w/out BOTH username & API token silently ignores the other input parameter

[mcallaghan-bsm]

see https://github.com/fabiano/dotnet-ossindex/blob/master/DotNetOSSIndex/Program.cs#L210

            if (!string.IsNullOrEmpty(Username) && !string.IsNullOrEmpty(ApiToken))
            {
                var bytes = Encoding.UTF8.GetBytes($"{Username}:{ApiToken}");
                var value = Convert.ToBase64String(bytes);

                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", value);
            }

$ dotnet-ossindex --help
A .NET Core global tool to check the packages for known vulnerabilities.

Usage: dotnet ossindex [options] <Path>

Arguments:
  Path                        The path to a .sln, .csproj or .vbproj file

Options:
  -u|--username <USERNAME>    OSS Index Username
  -a|--api-token <API_TOKEN>  OSS Index API Token
  -?|-h|--help                Show help information

It wasn't clear to us that BOTH the username and the token were required, so when we were making requests, we started only supplying the token; and the tool didn't complain or reject;

As a precaution, it would be great if the tool does sanity check here; something like:

            if (!string.IsNullOrEmpty(Username) || !string.IsNullOrEmpty(ApiToken))
           >> ERROR, must supply both `--api-token` and `--username`