change subsetting for julia 1.0 compatibility

Author: vlepori

src/elasticarray.jl

@@ -118,7 +118,7 @@ end
 
 function Base.deleteat!(A::ElasticArray{T,N}, idxs::NTuple{N,Union{Tuple{},Int,Vector{Int},UnitRange{Int}}}) where {T,N}
     d = ndims(A)
-    prod(isempty.(first(idxs, length(idxs) - 1))) || throw(ArgumentError("Can only delete elements in the last dimension of A"))
+    prod(isempty.(idxs[1:end-1])) || throw(ArgumentError("Can only delete elements in the last dimension of A"))
     issubset(last(idxs), axes(A, d)) || throw(BoundsError(A, (ntuple(_->:,d-1)..., last(idxs))))
     keep = setdiff(axes(A, d), last(idxs))
     copyto!(A, selectdim(A, d, keep))