This is at commit 1955ef93b76e51cab5bed4c90f7eb9df7035355a on the master branch, plus some local patches on my private branch which I suspect are irrelevant to this:
--8<---------------cut here---------------start------------->8--- mhw@jojen ~$ guix graph --path gtk+ imagemagick Backtrace: In ice-9/boot-9.scm: 1736:10 13 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _) In unknown file: 12 (apply-smob/0 #<thunk 7fc164214520>) In ice-9/boot-9.scm: 718:2 11 (call-with-prompt _ _ #<procedure default-prompt-handler (k proc)>) In ice-9/eval.scm: 619:8 10 (_ #(#(#<directory (guile-user) 7fc164217c80>))) In guix/ui.scm: 2164:12 9 (run-guix-command _ . _) In guix/scripts/graph.scm: 573:2 8 (guix-graph . _) In ice-9/boot-9.scm: 1736:10 7 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _) 1731:15 6 (with-exception-handler #<procedure 7fc1619c88d0 at ice-9/boot-9.scm:1815:7 (exn)> _ #:unwind? _ #:unwind-for-type _) 1736:10 5 (with-exception-handler _ _ #:unwind? _ #:unwind-for-type _) In guix/store.scm: 636:37 4 (thunk) In guix/scripts/graph.scm: 598:37 3 (_ #<store-connection 256.99 7fc1619d4780>) 598:37 2 (_ #f) In ice-9/boot-9.scm: 1669:16 1 (raise-exception _ #:continuable? _) 1669:16 0 (raise-exception _ #:continuable? _) ice-9/boot-9.scm:1669:16: In procedure raise-exception: Wrong type to apply: #<syntax-transformer set-grafting> mhw@jojen ~$ --8<---------------cut here---------------end--------------->8---