I was trying to get Surrogates.jl to work on my computer but ended up with this error after trying to re-update to the current version of DiffEqFlux. Now I can’t add any packages, and Pkg.resolve() and Pkg.update() also throw this error.
Long story short, DataStructures broke a ton in a really weird way and https://github.com/JuliaRegistries/General/pull/20420 is the end of this saga. Sorry.
Should be fixed now. Sorry for the confusion.