target_class should not be TT_ICLASS; close #1152

src/vm.c

@@ -873,7 +873,13 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
       else {
         ci->argc = n;
       }
-      ci->target_class = c;
+      if (c->tt == MRB_TT_ICLASS) {
+        ci->target_class = c->c;
+      }
+      else {
+        ci->target_class = c;
+      }
+
       ci->pc = pc + 1;
       ci->acc = a;