`Assertion failed: (isa<To>(Val) && "cast<Ty>() argument of incompatible type!")` failure

@vchuravy asked me to open an issue so that we don't lose track of this. Gist of the full output is [here](https://gist.github.com/kshyatt/6daa2cf574292a83a78b585ee21dbdec). Unfortunately I don't have an MWE (yet). Valentin suggested I run what I have locally with: > And your log has a truncated fieldtypes and a missing LLVMType :sad: > you have to go in and create a direct `@ccall jl_()` But I'm not sure how to do this, if anyone has any guidance that would be great.