when x is the identity, f = sign(x) works while g = sign(x) - x fails because arclength is called with invalid signiture

[macd]

Here is all the info
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| | || | | | (| | | Version 1.11.1 (2024-10-16)
/ |_'|||_'_| | Official https://julialang.org/ release
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julia> using ApproxFun

(@v1.11) pkg> status ApproxFun
Status ~/julia-versions/dot_julia/environments/v1.11/Project.toml
[28f2ccd6] ApproxFun v0.13.27

julia> x = Fun(identity, -1..1)
Fun(Chebyshev(-1 .. 1), [0.0, 1.0])

julia> f = sign(x) # this works
Fun(Chebyshev(Segment(-1.0, 0.0)) ⨄ Chebyshev(Segment(0.0, 1.0)), [-1.0, 1.0])

julia> g = sign(x) - x
ERROR: MethodError: no method matching arclength(::DomainSets.Point{Float64})
The function arclength exists, but no method is defined for this combination of argument types.

Closest candidates are:
arclength(::ApproxFunBase.EmptyDomain)
...