Check `arena_idx` before accessing; fix
MODIFY
src/error.c
src/error.c
@@ -229,7 +229,8 @@ mrb_exc_set(mrb_state *mrb, mrb_value exc)
}
else {
mrb->exc = mrb_obj_ptr(exc);
- if ((struct RBasic*)mrb->exc == mrb->gc.arena[mrb->gc.arena_idx-1]) {
+ if (mrb->gc.arena_idx > 0 &&
+ (struct RBasic*)mrb->exc == mrb->gc.arena[mrb->gc.arena_idx-1]) {
mrb->gc.arena_idx--;
}
if (!mrb->gc.out_of_memory) {

Check `arena_idx` before accessing; fix #3934