julia> using CUDA, NonlinearSolve; CUDA.allowscalar(false)                                         
                                                 
julia> x = ComponentArray(; x = ones(2), y = ones(2)) |> cu              
ComponentVector{Float32, CuArray{Float32, 1, CUDA.DeviceMemory}, Tuple{Axis{(x = 1:2, y = 3:4)}}}(x = Float32[1.0, 1.0], y = Float32[1.0, 1.0])                                                       
                                                                                                   
julia> NonlinearSolveBase.L2_NORM(x)                                                               
ERROR: Scalar indexing is disallowed.                                                              
Invocation of getindex resulted in scalar indexing of a GPU array.                                 
This is typically caused by calling an iterating implementation of a method.                       
Such implementations *do not* execute on the GPU, but very slowly on the CPU,
and therefore should be avoided.