Critical: Vector of Vector raise Exception

[dmoliveira]

Hi there! I wanted to report an issue with the write function in the JSON3 library. When I tried to use it to translate a vector into a valid JSON string, I found that using an empty array as [] works correctly, but [[]] does not. Could the team please look into this issue and consider fixing it? It's a simple use case that is currently not functioning as expected. Thank you!

1. Example for empty vector: OK

using JSON3
julia> JSON3.write([])
"[]"

2. Example for an empty vector instead of another vector: Error

julia> JSON3.write([[]])
ERROR: BoundsError: attempt to access 2-element Vector{UInt8} at index [3]
Stacktrace:
 [1] setindex!(A::Vector{UInt8}, x::UInt8, i1::Int64)
   @ Base ./array.jl:966
 [2] write(::StructTypes.ArrayType, buf::Vector{UInt8}, pos::Int64, len::Int64, x::Vector{Any}; kw::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
   @ JSON3 ~/.julia/packages/JSON3/CpNms/src/write.jl:71
 [3] write(::StructTypes.ArrayType, buf::Vector{UInt8}, pos::Int64, len::Int64, x::Vector{Any})
   @ JSON3 ~/.julia/packages/JSON3/CpNms/src/write.jl:165
 [4] write(::StructTypes.ArrayType, buf::Vector{UInt8}, pos::Int64, len::Int64, x::Vector{Vector{Any}}; kw::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
   @ JSON3 ~/.julia/packages/JSON3/CpNms/src/write.jl:170
 [5] write
   @ ~/.julia/packages/JSON3/CpNms/src/write.jl:165 [inlined]
 [6] write(obj::Vector{Vector{Any}}; kw::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
   @ JSON3 ~/.julia/packages/JSON3/CpNms/src/write.jl:39
 [7] write(obj::Vector{Vector{Any}})
   @ JSON3 ~/.julia/packages/JSON3/CpNms/src/write.jl:36
 [8] top-level scope
   @ REPL[3]:1