eval: Replace a panic with ev.errorf.
eval: Replace a panic with ev.errorf.

elves/elvish,ke7ofi/elvish,elves/elvish,elves/elvish,beni55/elvish,ke7ofi/elvish,CodyGuo/elvish,beni55/elvish,CodyGuo/elvish,elves/elvish,elves/elvish