Overapproximate CH with 0-gens zonotope

[mforets]

julia> X = Zonotope([0.2553862516469573, 0.9780152852016689], Matrix{Float64}(undef, 2, 0));

julia> Y = Zonotope([0.6127892528289145, 0.827561464100999], [0.4943828526889149 0.20515399000349377; 0.9913211225797134 0.7315677123098985]);

julia> CH(X, Y)
ConvexHull{Float64, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}}(Zonotope{Float64, Vector{Float64}, Matrix{Float64}}([0.2553862516469573, 0.9780152852016689], Matrix{Float64}(undef, 2, 0)), Zonotope{Float64, Vector{Float64}, Matrix{Float64}}([0.6127892528289145, 0.827561464100999], [0.4943828526889149 0.20515399000349377; 0.9913211225797134 0.7315677123098985]))

julia> overapproximate(CH(X, Y), Zonotope)
ERROR: ArgumentError: the target order should be at least 1, but it is 0
Stacktrace:
 [1] reduce_order(Z::Zonotope{Float64, Vector{Float64}, Matrix{Float64}}, r::Int64, method::LazySets.GIR05) (repeats 2 times)
   @ LazySets ~/JuliaReach/LazySets.jl/src/Sets/Zonotope.jl:355
 [2] _overapproximate_convex_hull_zonotope_G05(X::ConvexHull{Float64, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}})
   @ LazySets.Approximations ~/JuliaReach/LazySets.jl/src/Approximations/overapproximate.jl:249
 [3] #overapproximate#9
   @ ~/JuliaReach/LazySets.jl/src/Approximations/overapproximate.jl:237 [inlined]
 [4] overapproximate(X::ConvexHull{Float64, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}, Zonotope{Float64, Vector{Float64}, Matrix{Float64}}}, ::Type{Zonotope})
   @ LazySets.Approximations ~/JuliaReach/LazySets.jl/src/Approximations/overapproximate.jl:236
 [5] top-level scope
   @ REPL[5]:1

Expected result:

julia> plot(X)

julia> plot!(Y)

julia> plot!(CH(X, Y))

julia> plot!(overapproximate(CH(X, Y), Zonotope), ls=:dash)