dont crash when there is not lyrics

src/commands/music/lyrics.ts

@@ -144,7 +144,7 @@ export default {
       });
     }
 
-    if (data && data.length > 0) {
+    if (data && data.length > 0 && data[0].plainLyrics !== null) {
       const title = data[0];
       const limit_desc = 4096;
       const nb_embed = Math.ceil(title.plainLyrics.length / limit_desc);