eachchunkof zero dimensional array should work

[felixcremer]

The following should work:

julia> DiskArrays.eachchunk(zeros(3,0))
ERROR: ArgumentError: Chunk sizes must be strictly positive
Stacktrace:
 [1] RegularChunks
   @ ~/.julia/packages/DiskArrays/uMiMX/src/chunks.jl:63 [inlined]
 [2] map (repeats 2 times)
   @ ./tuple.jl:409 [inlined]
 [3] DiskArrays.GridChunks(sizes::Tuple{Int64, Int64}, chunksizes::Tuple{Int64, Int64}; offset::Tuple{Int64, Int64})
   @ DiskArrays ~/.julia/packages/DiskArrays/uMiMX/src/chunks.jl:216
 [4] GridChunks
   @ ~/.julia/packages/DiskArrays/uMiMX/src/chunks.jl:215 [inlined]
 [5] estimate_chunksize(size::Tuple{Int64, Int64}, elsize::Int64)
   @ DiskArrays ~/.julia/packages/DiskArrays/uMiMX/src/chunks.jl:455
 [6] estimate_chunksize
   @ ~/.julia/packages/DiskArrays/uMiMX/src/chunks.jl:441 [inlined]
 [7] eachchunk(a::Matrix{Float64})
   @ DiskArrays ~/.julia/packages/DiskArrays/uMiMX/src/diskarray.jl:42
 [8] top-level scope
   @ REPL[189]:1