(package-error-package (nth-value 1 (ignore-errors (intern "FOO" :bar)))) ;; => #<UNBOUND>
(This is in anticipation of using cl-store, which when deserializing foreign code may call INTERN with an unknown package. An lfarm server handles the resulting package error. BTW lfarm runs fine on ABCL using PRINT/READ for serialization. With SBCL as a client it's a kind of FFI to java :)