ArrayPartition violates the documentation of eltype

Describe the bug 🐞

In some situations ArrayPartition violates the documentation of eltype:

eltype(type)

  Determine the type of the elements generated by iterating a collection...

But this is not always the case (see MWE below).

As I understand the ArrayPartition declares eltype as a type that all udnerlying elements can be promoted to.
This behaviour might be by design, but it has a real practical implication.
Perhaps can be fixed on ForwardDiff side by extra promoting, but this can have other weird edge cases.
At the very least this behaviour can be documented as desired?

Minimal Reproducible Example 👇

julia> v = ArrayPartition([ 0.0 ], [ 1 ])
([0.0], [1])

julia> for e in v
           @show e isa eltype(v)
       end
e isa eltype(v) = true
e isa eltype(v) = false # would expect `true` here

Environment (please complete the following information):

• Output of using Pkg; Pkg.status()

(jl_ZYBD4c) pkg> st
Status `/private/var/folders/kf/1t2_wf7n49sgxmzzmmgsb1j40000gn/T/jl_ZYBD4c/Project.toml`
  [731186ca] RecursiveArrayTools v3.26.0

• Output of versioninfo()

julia> versioninfo()
Julia Version 1.10.4
Commit 48d4fd48430 (2024-06-04 10:41 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin22.4.0)
  CPU: 10 × Apple M2 Pro
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, apple-m1)
Threads: 1 default, 0 interactive, 1 GC (on 6 virtual cores)