Speech to Text (GCP) Telegram Bot

SpeechToText.cs

using Google.Cloud.Speech.V1;
using Telegram.Bot;
using static Google.Cloud.Speech.V1.RecognitionConfig.Types;
dotenv.net.DotEnv.Load();
string TELEGRAM_BOT_TOKEN = Environment.GetEnvironmentVariable("TELEGRAM_BOT_TOKEN") ?? throw new NullReferenceException("TELEGRAM_BOT_TOKEN");
string GOOGLE_APPLICATION_CREDENTIALS = Environment.GetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS") ?? throw new NullReferenceException("GOOGLE_APPLICATION_CREDENTIALS");
string GOOGLE_APPLICATION_PROJECT_ID = Environment.GetEnvironmentVariable("GOOGLE_APPLICATION_PROJECT_ID") ?? throw new NullReferenceException("GOOGLE_APPLICATION_PROJECT_ID");
string GetTestFromSpeech(string FilePath)
{
    RecognitionConfig config = new()
    {
        Encoding = AudioEncoding.WebmOpus,
        SampleRateHertz = 16000,
        LanguageCode = LanguageCodes.Ukrainian.Ukraine
    };
    return SpeechClient.Create().Recognize(config, RecognitionAudio.FetchFromUri($"https://api.telegram.org/file/bot{TELEGRAM_BOT_TOKEN}/{FilePath}")).Results[0].Alternatives[0].Transcript; 
}
new TelegramBotClient(TELEGRAM_BOT_TOKEN).StartReceiving(new Telegram.Bot.Extensions.Polling.DefaultUpdateHandler(HandleUpdateAsync, HandleErrorAsync));
async Task HandleErrorAsync(ITelegramBotClient bc, Exception err, CancellationToken ct) => Console.WriteLine(err.Message);
async Task HandleUpdateAsync(ITelegramBotClient botClient, Telegram.Bot.Types.Update update, CancellationToken canccellationToken)
{
    if (update.Type != Telegram.Bot.Types.Enums.UpdateType.Message && update?.Message?.Type != Telegram.Bot.Types.Enums.MessageType.Audio && update?.Message?.Voice is null) return;
    Telegram.Bot.Types.File file = await botClient.GetFileAsync(update?.Message?.Voice?.FileId, canccellationToken);
    await botClient.SendTextMessageAsync(update.Message.Chat.Id, text: GetTestFromSpeech(file.FilePath));
}
Console.ReadKey(); 

Nuget:

- dotenv.net
- Google.Cloud.Speech.V1
- Telegram.Bot
- Telegram.Bot.Extensions.Polling