Confusing error in the performance tips page

[lee-ranaweer]

Hello, I am new to Julia. I was working through the examples on the performance tips page when I ran into this code in the types with values-as-parameters section. The example code is included below as well.

function array3(fillval, ::Val{N}) where N
    fill(fillval, ntuple(d->3, Val(N)))
end

function filter3(A::AbstractArray{T,N}) where {T,N}
    kernel = array3(1, Val(N))
    filter(A, kernel)
end

There seems to be an error when the example calls filter() with an AbstractArray as an argument where a function is expected.

[kimikage]

xref: https://discourse.julialang.org/t/potential-error-in-the-performance-tips-page/113286