pathom 2.2.6 is released on clojars, this fixes a nasty bug on p/error-str that was returning a class type instead of string when the error didn't have message or data (which happens in NPE), this was breaking the transit output for some users, this version fixes it, thanks @pauld and @noxdeleo for the reports

Add new section to the book about how to debug exceptions: https://wilkerlucio.github.io/pathom/#_debugging_exceptions