Fix an error message.

Minimum tensor rank should be (dim + 1) instead of (dim).

Example:
    tf.argmin(x, 1)  # x is a 1-d vector.
before:
    "InvalidArgumentError: Minimum tensor rank: 1 but got: 1"
after:
    "InvalidArgumentError: Minimum tensor rank: 2 but got: 1"

Author: Thomas Lee

tensorflow/core/kernels/argmax_op.cc

@@ -59,7 +59,7 @@ class ArgOp : public OpKernel {
 
     OP_REQUIRES(context, dim >= 0, errors::InvalidArgument("dim must be >= 0"));
     OP_REQUIRES(context, dim < input_dims,
-                errors::InvalidArgument("Minimum tensor rank: ", dim,
+                errors::InvalidArgument("Minimum tensor rank: ", dim + 1,
                                         " but got: ", input_dims));
     OP_REQUIRES(
         context, input.dim_size(dim) > 0,