I was playing around, and inspected the boid count control to see if I might manually update it and see what unreasonably large and small populations look like. I saw the connected callback triggered updateProperty. Running updateProperty("boidCount", 10) in the console yielded a field with 10 boids, as expected, but apparently it doesn't update something else the natural code would, as as soon as two of the boids collided, a humongous explosion of boids occurred, like a firework.