connector/reactions: return error if not logged in

Previously, the getAvailableReactions function was only called with a
logged in client. However, now that it is called in the GetCapabilities
call, the client is no longer guaranteed to be logged in.

This was causing an NPE due to the (*TelegramClient).client being nil.

This commit makes the getAvailableReactions function not panic when the
client is not logged in.

Signed-off-by: Sumner Evans <sumner.evans@automattic.com>

pkg/connector/telegram.go

@@ -3,6 +3,7 @@ package connector
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"slices"
 	"strings"
@@ -907,6 +908,10 @@ func (t *TelegramClient) getAvailableReactionsForCapability(ctx context.Context)
 }
 
 func (t *TelegramClient) getAvailableReactions(ctx context.Context) (map[string]struct{}, error) {
+	if !t.IsLoggedIn() {
+		return nil, errors.New("you must be logged in to get available reactions")
+	}
+
 	log := zerolog.Ctx(ctx).With().Str("handler", "get_available_reactions").Logger()
 	t.availableReactionsLock.Lock()
 	defer t.availableReactionsLock.Unlock()