Constructor from Array{Nullable} gives eltype Nullable{Nullable}

[nalimilan]

Looks like Array{Nullable} isn't handled like Array{Nullable{T}}:

julia> nm = NullableArray(Nullable[Nullable() 0.0; 0.0 1.0])
2x2 NullableArrays.NullableArray{Nullable{T},2}:
 Nullable{Union{}}()  Nullable(0.0)
 Nullable(0.0)        Nullable(1.0)

[davidagold]

Those should be consistent. And we should probably remark somewhere that the way to create a NullableArray{Nullable{T}} is by means of NullableArray{Nullable{T}}(...).