This is a creative superflat world hosted on my own desktop.

Basically, I spawned an Allay using a spawn egg and named it King, after King from the Owl House. I gave it a note block to hold and then placed one down at my base to summon it towards a specific area. The last thing that happened before the seemingly random crash was me tuning the note block and then powering it with a lever, not directly on the note block but on the grass next to it.