Error when creating PeriodicSystem with empty positions

[nhz2]

Thank you for creating the high-level PeriodicSystems interface, it has simplified my simulation code.

My simulations typically start without particles and more get added at random times. This makes it tricky to use with PeriodicSystems because currently, it errors if I make a system without particles, see below.

Currently, I am constructing the PeriodicSystem with a few junk particles, and separately keeping track of if it is valid or not. It would simplify my code if PeriodicSystem could properly handle the case of no particles.

using StaticArrays
using CellListMap.PeriodicSystems
Vec2D = SVector{2,Float64}
system = PeriodicSystem(;
    positions=Vec2D[],
    cutoff=0.1,
    unitcell=[1.0, 1.0],
    output=0.0,
)

ERROR: DivideError: integer division error
Stacktrace:
 [1] rem
   @ ./int.jl:289 [inlined]
 [2] set_idxs!(idxs::Vector{UnitRange{Int64}}, n_particles::Int64, nbatches::Int64)
   @ CellListMap ~/.julia/packages/CellListMap/A9riF/src/CellLists.jl:414
 [3] CellListMap.AuxThreaded(cl::CellListMap.CellList{2, Float64}; particles_per_batch::Int64)
   @ CellListMap ~/.julia/packages/CellListMap/A9riF/src/CellLists.jl:392
 [4] AuxThreaded
   @ ~/.julia/packages/CellListMap/A9riF/src/CellLists.jl:373 [inlined]
 [5] #UpdateCellList!#52
   @ ~/.julia/packages/CellListMap/A9riF/src/CellLists.jl:687 [inlined]
 [6] CellListMap.CellList(x::Vector{SVector{2, Float64}}, box::CellListMap.Box{CellListMap.OrthorhombicCell, 2, Float64, Float64, 4}; parallel::Bool, nbatches::Tuple{Int64, Int64})
   @ CellListMap ~/.julia/packages/CellListMap/A9riF/src/CellLists.jl:506
 [7] PeriodicSystem(; positions::Vector{SVector{2, Float64}}, xpositions::Nothing, ypositions::Nothing, unitcell::Vector{Float64}, cutoff::Float64, output::Float64, output_name::Symbol, parallel::Bool, nbatches::Tuple{Int64, Int64}, lcell::Int64)
   @ CellListMap.PeriodicSystems ~/.julia/packages/CellListMap/A9riF/src/PeriodicSystems.jl:165
 [8] top-level scope
   @ REPL[10]:1

[lmiq]

This is fixed in 0.8.5 to be available at any moment.