Issue with OrdinaryDiffEq.jl when using an ArrayPartition of Arrays of StaticArrays

OrdinaryDiffEq.jl has an issue with ArrayPartitions constructed from nested arrays of StaticArrays. The following MWE

using StaticArrays, StructArrays
using RecursiveArrayTools
using OrdinaryDiffEq

u1 = StructArray{SVector{2, Float64}}(ntuple(x -> x * ones(10), 2))
u2 = deepcopy(u1)
u = ArrayPartition(u1, u2)

function rhs!(du, u, p, t) 
    du .= u
end
prob = ODEProblem(rhs!, u, (0, 1.0))
sol = solve(prob, Tsit5())

yields the stacktrace

ERROR: MethodError: Cannot `convert` an object of type Float64 to an object of type SVector{2, Float64}
Closest candidates are:
  convert(::Type{SA}, ::Tuple) where SA<:StaticArray at ~/.julia/packages/StaticArrays/0T5rI/src/convert.jl:171
  convert(::Type{SA}, ::SA) where SA<:StaticArray at ~/.julia/packages/StaticArrays/0T5rI/src/convert.jl:170
  convert(::Type{SA}, ::StaticArray{S}) where {SA<:StaticArray, S<:Tuple} at ~/.julia/packages/StaticArrays/0T5rI/src/convert.jl:164
  ...
Stacktrace:
  [1] maybe_convert_elt(#unused#::Type{SVector{2, Float64}}, vals::Float64)
    @ StructArrays ~/.julia/packages/StructArrays/rICDm/src/utils.jl:197
  [2] setindex!
    @ ~/.julia/packages/StructArrays/rICDm/src/structarray.jl:363 [inlined]
  [3] macro expansion
    @ ./broadcast.jl:961 [inlined]
  [4] macro expansion
    @ ./simdloop.jl:77 [inlined]
  [5] copyto!
    @ ./broadcast.jl:960 [inlined]
  [6] copyto!
    @ ./broadcast.jl:913 [inlined]
  [7] f
    @ ~/.julia/packages/RecursiveArrayTools/YoTgv/src/array_partition.jl:327 [inlined]
  [8] ntuple
    @ ./ntuple.jl:49 [inlined]
  [9] copyto!
    @ ~/.julia/packages/RecursiveArrayTools/YoTgv/src/array_partition.jl:329 [inlined]
 [10] materialize!
    @ ./broadcast.jl:871 [inlined]
 [11] materialize!
    @ ./broadcast.jl:868 [inlined]
 [12] fast_materialize!
    @ ~/.julia/packages/FastBroadcast/fkwMa/src/FastBroadcast.jl:47 [inlined]
 [13] ode_determine_initdt(u0::ArrayPartition{Float64, Tuple{StructVector{SVector{2, Float64}, Tuple{Vector{Float64}, ....

I'm not sure but this seems to be related to the fact that eltype of ArrayPartitions of AbstractArray{<:StaticArray{N,T}} is T rather than StaticArray{N,T}.

Start by running the supplied MWE with StaticArrays, StructArrays, RecursiveArrayTools, and OrdinaryDiffEq. Inspect src/array_partition.jl around the copyto! implementation at lines 327-329, along with the reported eltype behavior and StructArrays conversion stacktrace. Done means the MWE no longer raises the Float64-to-SVector conversion MethodError.