Backtrace:
          19 (apply-smob/0 #<thunk 7f26c77982a0>)
In ice-9/boot-9.scm:
    724:2 18 (call-with-prompt _ _ #<procedure default-prompt-handle…>)
In ice-9/eval.scm:
    619:8 17 (_ #(#(#<directory (guile-user) 7f26c779dc80>)))
In guix/ui.scm:
   2399:7 16 (run-guix . _)
  2362:10 15 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1752:10 14 (with-exception-handler _ _ #:unwind? _ # _)
In guix/status.scm:
    842:4 13 (call-with-status-report _ _)
In ice-9/boot-9.scm:
  1752:10 12 (with-exception-handler _ _ #:unwind? _ # _)
    152:2 11 (with-fluid* _ _ _)
In unknown file:
          10 (_ #<procedure 7f26c16d2d00 at ice-9/eval.scm:330:13 ()> …)
In ice-9/boot-9.scm:
    152:2  9 (with-fluid* _ _ _)
    152:2  8 (with-fluid* _ _ _)
    724:2  7 (call-with-prompt ("build handler") #<procedure 7f2693…> …)
In guix/ui.scm:
  1306:18  6 (_ #<partial-continuation 7f2693e3e820> _ _ _)
   1097:9  5 (show-what-to-build #<store-connection 256.100 7f26c15…> …)
In guix/derivations.scm:
   377:17  4 (substitution-oracle _ _ #:mode _)
In srfi/srfi-1.scm:
   460:18  3 (fold #<procedure 7f26c136bfd0 at guix/derivations.scm…> …)
In guix/serialization.scm:
   259:20  2 (_ #<<substitutable> path: "/gnu/store/05c9fyy44bw1q40…> …)
In ice-9/boot-9.scm:
  1685:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
error: <substitutable>: unbound variable