Sometimes, when SoundBounds attempts to load a new song it will crash due to Minecraft not loading audio data. Anecdotally, it seems more likely to occur when a player warps to a new location that contains music. I believe it's caused by SoundBounds attempting to load the same song multiple times simultaneously, will try to guard against it with synchronized blocks.

Example crashlog (note multiple threads in stacktrace): crash-2021-08-16_01.00.33-client.txt