Another fix for single-sticker packs

Co-authored-by: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>

ts/types/Stickers.ts

@@ -706,7 +706,7 @@ async function doDownloadStickerPack(
     });
 
     const successfulStickerCount = jobResults.filter(item => item).length;
-    if (successfulStickerCount === 0) {
+    if (successfulStickerCount === 0 && nonCoverStickers.length !== 0) {
       throw new Error('doDownloadStickerPack: All stickers failed to download');
     }