Fix error message in autograd (#39729)

Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/39729

Differential Revision: D21953429

Pulled By: albanD

fbshipit-source-id: 76aea69c5100371daaee7e5e386aac05e0b6a438
diff --git a/torch/csrc/autograd/autograd.cpp b/torch/csrc/autograd/autograd.cpp
index f5a3c29..ab02a03 100644
--- a/torch/csrc/autograd/autograd.cpp
+++ b/torch/csrc/autograd/autograd.cpp
@@ -81,8 +81,7 @@
     }
     TORCH_CHECK(
         gradient_edge.function,
-        "element ", i, " of tensors does not require grad and does not have a grad_fn",
-        i);
+        "element ", i, " of tensors does not require grad and does not have a grad_fn");
     roots.push_back(std::move(gradient_edge));
   }