fix micro smarcio

backend/src/app.py

@@ -210,6 +210,9 @@ def add_song():
         ## song not found, downolad from YT
         yt_video_id = yt_search_song(info.title, info.artist)
 
+        if yt_video_id is None:
+            return error("No video found on youtube")
+
         ## add in DB
         song = Song(
             uuid=str(uuid.uuid4()),