In Julia 1.5 use custom hints to replace debug mode?

[oxinabox]

Right now we use debug mode (#136) with the special error type for addition of composites to primals failing, to give instructions on how to overload things to fix this.
But in julia 1.5 there is special functionality for adding hints for how to resolve errors build in by some magic:
JuliaLang/julia#35094

ChainRulesCore.jl/src/differentials/composite.jl

Lines 233 to 254 in 1be9bc4

	struct PrimalAdditionFailedException{P} <: Exception
	primal::P
	differential::Composite{P}
	original::Exception
	end
	function Base.showerror(io::IO, err::PrimalAdditionFailedException{P}) where {P}
	println(io, "Could not construct $P after addition.")
	println(io, "This probably means no default constructor is defined.")
	println(io, "Either define a default constructor")
	printstyled(io, "$P(", join(propertynames(err.differential), ", "), ")", color=:blue)
	println(io, "\nor overload")
	printstyled(io,
	"ChainRulesCore.construct(::Type{$P}, ::$(typeof(err.differential)))";
	color=:blue
	)
	println(io, "\nor overload")
	printstyled(io, "Base.:+(::$P, ::$(typeof(err.differential)))"; color=:blue)
	println(io, "\nOriginal Exception:")
	printstyled(io, err.original; color=:yellow)
	println(io)
	end