Update src/config.jl

Author: ChrisRackauckas

src/config.jl

@@ -301,8 +301,8 @@ This constructor does not store/modify `x`.
 function HessianConfig(f::F,
                        result::DiffResult,
                        x::AbstractArray{V},
-                       chunk::Chunk,
-                       tag) where {F,V}
+                       chunk::Chunk  = Chunk(x),
+                       tag = Tag(f, V)) where {F,V}
     jacobian_config = JacobianConfig((f,gradient), DiffResults.gradient(result), x, chunk, tag)
     gradient_config = GradientConfig(f, jacobian_config.duals[2], chunk, tag)
     return HessianConfig(jacobian_config, gradient_config)