`map(f)` allocates infinite amount of memory

This overload:
https://github.com/JuliaArrays/AxisArrays.jl/blob/bbf1f27e3a185353a62a83587de5762bbfde7173/src/core.jl#L431-L435
can be called with an empty As, e.g. map(x->x). This calls matchingdims(()) which calls something like tuple(zip()...):
https://github.com/JuliaArrays/AxisArrays.jl/blob/bbf1f27e3a185353a62a83587de5762bbfde7173/src/combine.jl#L12-L13
Since zip() is an infinite iterator of empty tuples, Julia allocates an infinite amount of memory which is quite unexpected in this case (I stumbled upon this when I forgot an argument to map while using a package that has AxisArrays in its dependency graph and got Julia OOM-killed).
I believe this should be a MethodError instead, e.g. by requiring at least one array:

function Base.map(f, A::AxisArray{T,N,D,Ax}, As::AxisArray{T,N,D,Ax}...) where {T,N,D,Ax<:Tuple{Vararg{Axis}}}
    matchingdims((A, As...)) || error("All axes must be identically-valued")
    data = map(a -> a.data, (A, As...))
    return AxisArray(map(f, data...), A.axes...)
end

Maybe changing matchingdims(()) behavior makes sense as well.

Start with the AxisArray map overload in src/core.jl at lines 431-435, then inspect matchingdims in src/combine.jl at lines 12-13. Reproduce map(x -> x) with no array arguments and verify it fails promptly with a MethodError or equivalent error instead of allocating indefinitely. Check that normal map calls with one or more AxisArrays still work.