[Bug fix] Link Play song idx too big error

- Fix a bug that if song's idx is too big, the server will catch the error, which makes Link Play cannot work.
- For Arcaea 6.4.0/1

latest version/core/linkplay.py

@@ -23,6 +23,8 @@ def get_song_unlock(client_song_map: 'dict[str, list]') -> bytes:
             if not v[i]:
                 continue
             index = int(k) * 5 + i
+            if index >= Constant.LINKPLAY_UNLOCK_LENGTH * 8:
+                continue
             user_song_unlock[index // 8] |= 1 << (index % 8)
 
     return bytes(user_song_unlock)