try.html gives an error on the new predicate guards

[AlexDikelsky]

If I try to run this code, I get the error message s is undefined.

[mlochbaum]

This is a runtime error because the predicate fails, indicating that it should go to the next body, but there are none left. Error formatting is failing here; I'll have to figure out why tomorrow morning.

[mlochbaum]

It actually failed to throw an error and returned undefined, which isn't a valid BQN value. I'd missed it because predicates made a previously unreachable part of the compiled JS reachable.