Update src/config.jl

Author: ChrisRackauckas

src/config.jl

@@ -175,8 +175,8 @@ This constructor does not store/modify `x`.
 """
 function GradientConfig(f::F,
                         x::AbstractArray{V},
-                        ::Chunk{N},
-                        ::T) where {F,V,N,T}
+                        ::Chunk{N}  = Chunk(x),
+                        ::T = Tag(f, V)) where {F,V,N,T}
     seeds = construct_seeds(Partials{N,V})
     duals = similar(x, Dual{T,V,N})
     return GradientConfig{T,V,N,typeof(duals)}(seeds, duals)