I had once something similar with a small stone. Lucky nothing bend, just had a not so pleasant stop.
I‘m not sure if I would like to have a weak link which might fail in the wrong moment.
Best way is probably really to just make the chain running enclosed.
But than I guess you use 42th sprockets the clearance is even less than it is already.
I still don’t know what to do for my next Bro build … new chain drive or Gear drive … when you have test the helical e-toxx GD it’s hard to go back to chain also hard time thinking
Same thing happened to me only the stick didn’t wreak havoc on my drivetrain. I think a smaller wheel sprocket and maybe protective guards like many belt systems use would help reduce the chance or stop this from happening.
This isn’t a chain drive specific issue, I have had this happen with a belt drive as well when a small stone got stuck in it. Not with quite such a dramatic effect on the drive train though.