class.c: `const_missing` do not have to be in the backtrace; ref
@@ -2460,6 +2460,7 @@ mrb_mod_const_missing(mrb_state *mrb, mrb_value mod)
mrb_sym sym;
mrb_get_args(mrb, "n", &sym);
+ mrb->c->ci->mid = 0;
if (mrb_class_real(mrb_class_ptr(mod)) != mrb->object_class) {
mrb_name_error(mrb, sym, "uninitialized constant %v::%n", mod, sym);
