variable.c: refactor `mrb_vm_const_get` function.

src/variable.c

@@ -803,9 +803,9 @@ mrb_vm_const_get(mrb_state *mrb, mrb_sym sym)
   struct RClass *c;
   struct RClass *c2;
   mrb_value v;
-  const struct RProc *proc;
+  const struct RProc *proc = mrb->c->ci->proc;
 
-  c = MRB_PROC_TARGET_CLASS(mrb->c->ci->proc);
+  c = MRB_PROC_TARGET_CLASS(proc);
   if (!c) c = mrb->object_class;
   if (iv_get(mrb, c->iv, sym, &v)) {
     return v;
@@ -821,8 +821,7 @@ mrb_vm_const_get(mrb_state *mrb, mrb_sym sym)
     c2 = mrb_class_ptr(klass);
   }
   if (c2 && (c2->tt == MRB_TT_CLASS || c2->tt == MRB_TT_MODULE)) c = c2;
-  mrb_assert(!MRB_PROC_CFUNC_P(mrb->c->ci->proc));
-  proc = mrb->c->ci->proc;
+  proc = proc->upper;
   while (proc) {
     c2 = MRB_PROC_TARGET_CLASS(proc);
     if (c2 && iv_get(mrb, c2->iv, sym, &v)) {