Prevent runtime panic in case telegram not initialised

Fix for #90

provider/telegram.go

@@ -192,9 +192,15 @@ func (th *TelegramHandler) LoginHandler(w http.ResponseWriter, r *http.Request)
 		token, err := randToken()
 		if err != nil {
 			rest.SendErrorJSON(w, r, th.L, http.StatusInternalServerError, err, "failed to generate code")
+			return
 		}
 
 		th.requests.Lock()
+		if th.requests.data == nil {
+			th.requests.Unlock()
+			rest.SendErrorJSON(w, r, th.L, http.StatusInternalServerError, errors.New("run goroutine is not running"), "failed to process login request")
+			return
+		}
 		th.requests.data[token] = tgAuthRequest{
 			expires: time.Now().Add(tgAuthRequestLifetime),
 		}

provider/telegram_test.go

@@ -12,15 +12,38 @@ import (
 	"testing"
 	"time"
 
-	authtoken "github.com/go-pkgz/auth/token"
 	"github.com/stretchr/testify/assert"
+
+	authtoken "github.com/go-pkgz/auth/token"
 )
 
 // same across all tests
 var botInfoFunc = func(ctx context.Context) (*botInfo, error) {
 	return &botInfo{Username: "my_auth_bot"}, nil
 }
 
+func TestTgLoginHandlerErrors(t *testing.T) {
+	tg := TelegramHandler{
+		ProviderName: "telegram",
+		ErrorMsg:     "❌ Invalid auth request. Please try clicking link again.",
+		SuccessMsg:   "✅ You have successfully authenticated!",
+		Telegram:     NewTelegramAPI("test", http.DefaultClient),
+	}
+
+	r := httptest.NewRequest("GET", "/login", nil)
+	w := httptest.NewRecorder()
+	tg.LoginHandler(w, r)
+	assert.Equal(t, 500, w.Code, "request should succeed")
+
+	var resp = struct {
+		Error string `json:"error"`
+	}{}
+
+	err := json.Unmarshal(w.Body.Bytes(), &resp)
+	assert.Nil(t, err)
+	assert.Equal(t, "failed to process login request", resp.Error)
+}
+
 func TestTelegramUnconfirmedRequest(t *testing.T) {
 	m := &TelegramAPIMock{
 		GetUpdatesFunc: func(ctx context.Context) (*telegramUpdate, error) {