Need to set `ci->proc` when we have `RProc` structure.
Mentioned in
MODIFY
src/vm.c
src/vm.c
@@ -475,6 +475,9 @@ mrb_funcall_with_block(mrb_state *mrb, mrb_value self, mrb_sym mid, mrb_int argc
int ai = mrb_gc_arena_save(mrb);
ci->acc = CI_ACC_DIRECT;
+ if (MRB_METHOD_PROC_P(m)) {
+ ci->proc = MRB_METHOD_PROC(m);
+ }
val = MRB_METHOD_CFUNC(m)(mrb, self);
mrb->c->stack = mrb->c->ci->stackent;
cipop(mrb);

Need to set `ci->proc` when we have `RProc` structure.

Mentioned in https://qiita.com/bamchoh/items/eabebbbb330cb0e0470a