check if block is given in eval_under(); fix #2486

1 files changed, 3 insertions, 0 deletions

diff --git a/src/vm.c b/src/vm.c
index 33e8eefb3..d4a8fd68d 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -484,6 +484,9 @@ eval_under(mrb_state *mrb, mrb_value self, mrb_value blk, struct RClass *c)
   struct RProc *p;
   mrb_callinfo *ci;
 
+  if (mrb_nil_p(blk)) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "no block given");
+  }
   ci = mrb->c->ci;
   if (ci->acc == CI_ACC_DIRECT) {
     return mrb_yield_with_class(mrb, blk, 0, 0, self, c);