Typo

theano/tensor/extra_ops.py

@@ -43,7 +43,7 @@ class DiffOp(theano.Op):
         inputs = inputs[0]
 
         if inputs.ndim != 1:
-            raise TypeError("Grad is not implemented for inputs with"
+            raise NotImplementedError("Grad is not implemented for inputs with"
                                       "number of dimension other than 1.")
 
         z = outputs_gradients[0]