[Macha]

I had the opposite problem where using my (recent-ish) cheap midi keyboard with WebMidi was crashing Firefox.

[halfradaition]

That's usually caused by cheap controller firmware flooding the connection with continuous Active Sensing signals (0xFE bytes every 300ms) or noisy clock jitter.

[im3w1l]

That's one way to look at it, but imo firefox shouldnt crash no matter how malformed the data is.