Scalar indexing on GPU when computing `Zygote.gradient` of `dot(x::CA, x::CA)`

julia> Zygote.gradient(x -> dot(x, x), CUDA.ones(4)) # works
(Float32[2.0, 2.0, 2.0, 2.0],)

julia> Zygote.gradient(x -> dot(x, x), (;x=ones(4)) |> ComponentArray |> cu)                                                                                                                          
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 are only permitted from the REPL for prototyping purposes.                                                                                                                              
If you did intend to index this array, annotate the caller with @allowscalar.                                                                                                                         
Stacktrace:                                                                                        
  [1] error(s::String)                           
    @ Base ./error.jl:35                                                                           
  [2] assertscalar(op::String)                                                                     
    @ GPUArraysCore ~/.julia/packages/GPUArraysCore/uOYfN/src/GPUArraysCore.jl:103                                                                                                                    
  [3] getindex                                   
    @ ~/.julia/packages/GPUArrays/dAUOE/src/host/indexing.jl:48 [inlined]                                                                                                                             
  [4] getindex                                                                                                                                                                                        
    @ ~/.julia/dev/ComponentArrays/src/array_interface.jl:94 [inlined]                                                                                                                                
  [5] getindex                                   
    @ ~/.julia/packages/OffsetArrays/0MOrf/src/OffsetArrays.jl:436 [inlined]                                                                                                                          
  [6] _broadcast_getindex                                                                                                                                                                             
    @ ./broadcast.jl:675 [inlined]                                                                                                                                                                    
  [7] _getindex                                                                                                                                                                                       
    @ ./broadcast.jl:705 [inlined]                                                                                                                                                                    
  [8] _broadcast_getindex                        
    @ ./broadcast.jl:681 [inlined]                                                                 
  [9] getindex                                   
    @ ./broadcast.jl:636 [inlined]                                                                                                                                                                    
 [10] macro expansion                                                                                                                                                                                 
    @ ./broadcast.jl:1004 [inlined]                                                                
 [11] macro expansion                                                                              
    @ ./simdloop.jl:77 [inlined]                                                                   
 [12] copyto!                                    
    @ ./broadcast.jl:1003 [inlined]                                                                
 [13] copyto!                                    
    @ ./broadcast.jl:956 [inlined]                                                                 
 [14] copy                                       
    @ ./broadcast.jl:928 [inlined]                                                                 
 [15] materialize                                
    @ ./broadcast.jl:903 [inlined]                                                                 
 [16] accum(x::OffsetArrays.OffsetVector{…}, ys::OffsetArrays.OffsetVector{…})                                                                                                                        
    @ Zygote ~/.julia/packages/Zygote/YYT6v/src/lib/lib.jl:25                                                                                                                                         
 [17] accum                                      
    @ ComponentArraysZygoteExt ~/.julia/dev/ComponentArrays/ext/ComponentArraysZygoteExt.jl:10 [inlined]                                                                                              
 [18] (::Zygote.var"#75#76"{Zygote.Pullback{Tuple{var"#64#65", ComponentVector{…}}, Tuple{Zygote.ZBack{…}}}})(Δ::Float32)
    @ Zygote ~/.julia/packages/Zygote/YYT6v/src/compiler/interface.jl:45                                                                                                                              
 [19] gradient(f::Function, args::ComponentVector{Float32, CuArray{Float32, 1, CUDA.Mem.DeviceBuffer}, Tuple{Axis{…}}})                                                                               
    @ Zygote ~/.julia/packages/Zygote/YYT6v/src/compiler/interface.jl:97                                                                                                                              

Reproduce the gradient example and start with ext/ComponentArraysZygoteExt.jl, then inspect src/array_interface.jl and the stack-traced indexing paths. Determine why the ComponentArrays/Zygote gradient path performs scalar indexing on the GPU. Done means the shown gradient computation succeeds without the scalar-indexing error.