`sudo guix system reconfigure config.scm` fails on Guix commit 177bc62.
I'm attaching my config.scm. Here is my backtrace:

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/home/luther/config.scm:40:4: warning: 'title' field is deprecated
Backtrace:
In gnu/services.scm:
   778:26 19 (loop #<<service> type: #<service-type account 1f9fa00>…>)
In srfi/srfi-1.scm:
   592:29 18 (map1 (#<<service> type: #<service-type guix 27edc80…> …))
   592:29 17 (map1 (#<<service> type: #<service-type ntp 27ed5a0>…> …))
   592:17 16 (map1 (#<<service> type: #<service-type dbus 27ed9b0…> …))
In gnu/services.scm:
   778:26 15 (loop #<<service> type: #<service-type dbus 27ed9b0> va…>)
In srfi/srfi-1.scm:
   592:29 14 (map1 (#<<service> type: #<service-type elogind 27ed…> …))
   592:17 13 (map1 (#<<service> type: #<service-type polkit 27ed9…> …))
In gnu/services.scm:
   778:26 12 (loop #<<service> type: #<service-type polkit 27ed960> …>)
In srfi/srfi-1.scm:
   592:29 11 (map1 (#<<service> type: #<service-type elogind 27ed…> …))
   592:29 10 (map1 (#<<service> type: #<service-type colord 27ed0…> …))
   592:29  9 (map1 (#<<service> type: #<service-type cups-pk-help…> …))
   592:29  8 (map1 (#<<service> type: #<service-type accountsserv…> …))
   592:29  7 (map1 (#<<service> type: #<service-type udisks 27ed0…> …))
   592:29  6 (map1 (#<<service> type: #<service-type network-mana…> …))
   592:29  5 (map1 (#<<service> type: #<service-type gnome-deskto…> …))
   592:17  4 (map1 (#<<service> type: #<service-type localed 27ed82…>))
In gnu/services.scm:
   778:26  3 (loop #<<service> type: #<service-type localed 27ed820>…>)
In srfi/srfi-1.scm:
   592:17  2 (map1 (#<<service> type: #<service-type gdm 27ed730> v…>))
In gnu/services.scm:
   787:37  1 (loop #<<service> type: #<service-type gdm 27ed730> val…>)
In unknown file:
           0 (car ())

ERROR: In procedure car:
In procedure car: Wrong type (expecting pair): ()
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Luther