We're working an 'inner property into the next draft for chaining nested
errors together.

However, R6RS has a standard way to make compound conditions for that
purpose. Ideally, on R6RS systems, compound foreign statuses would be
represented by compound conditions.

<https://api.staging.scheme.org/static/r6rs-lib-errata-corrected.pdf>
page 26.

I assume no other systems have compound conditions except R6RS and maybe
Racket, though I can't find them in Racket's manual other than the R6RS
compatibility section. Common Lisp does not have them. Clojure
exceptions are java.lang.Exception subclasses, so unlikely as well.