clojure.tools.namespace.repl/refresh accepts symbol as named parameter :after. If this symbol cannot be resolved then this causes NullPointerException which is not helpful.
NullPointerException's stack trace:
It would be nice to verify result of 'resolve' and throw IllegalArgumentException with appropriate message. The change would be:
Used tools.namespace version 0.2.7
Fix included in release 0.2.8