Bug with Winston 0.15.2 and julia 1.7.1?

I have upgraded to julia 1.7.1 and I encounter a weird error perhaps related to the Winston library.

  julia> using Winston
  
  julia> flatten6(A) =  [[isa(x,Array) ? flatten6(x) : x for x in A]...;]
  flatten6 (generic function with 1 method)
  
  julia> flatten6(Any[1,Any[]])
  ERROR: DimensionMismatch("tried to assign 0 elements to 2 destinations")
  Stacktrace:
    [1] throw_setindex_mismatch(X::Vector{Any}, I::Tuple{Int64})
      @ Base ./indices.jl:191
    [2] setindex_shape_check
      @ ./indices.jl:245 [inlined]
    [3] setindex!
      @ ./array.jl:910 [inlined]
    [4] __cat_offset1!(A::Vector{Any}, shape::Tuple{Int64}, catdims::Tuple{Bool}, offsets::Tuple{Int64}, x::Vector{Any})
      @ Base ./abstractarray.jl:1731
    [5] __cat_offset!
      @ ./abstractarray.jl:1721 [inlined]
    [6] __cat_offset!
      @ ./abstractarray.jl:1722 [inlined]
    [7] __cat
      @ ./abstractarray.jl:1717 [inlined]
    [8] _cat_t
      @ ./abstractarray.jl:1713 [inlined]
    [9] #cat_t#136
      @ ./abstractarray.jl:1705 [inlined]
   [10] _cat
      @ ./abstractarray.jl:1703 [inlined]
   [11] #cat#141
      @ ./abstractarray.jl:1861 [inlined]
   [12] vcat(::Int64, ::Vector{Any})
      @ Base ./abstractarray.jl:1772
   [13] flatten6(A::Vector{Any})
      @ Main ./REPL[2]:1
   [14] top-level scope
      @ REPL[3]:1

If I don’t load Winston, I don’t get the error. Under a previous version of Julia (1.7 and I think 1.6.2), I was not getting the error, Winston loaded or not. I am not sure that this is a problem with Winston since it has seen no upgrade recently and no bug showed up with julia 1.7 and 1.6.2. Any hint about what is going wrong here?