set up smartparens during gerbil config

packages.el

@@ -31,8 +31,7 @@
 
 (defconst gerbil-packages
   '(evil-cleverparens
-    (gerbil-mode :location local)
-    smartparens)
+    (gerbil-mode :location local))
   "The list of Lisp packages required by the gerbil layer.
 
 Each entry is either:
@@ -66,11 +65,13 @@ Each entry is either:
     (add-to-list 'evil-lisp-safe-structural-editing-modes 'gerbil-mode)))
 
 (defun gerbil/init-gerbil-mode ()
-  (use-package gerbil-mode))
-
-(defun gerbil/post-init-smartparens ()
-  (with-eval-after-load 'smartparens
-    (sp-local-pair 'gerbil-mode "`" nil :actions nil)
-    (sp-local-pair 'gerbil-mode "'" nil :actions nil)))
+  (use-package gerbil-mode
+    :demand t
+    :config
+    (with-eval-after-load 'smartparens
+      (add-to-list 'sp--lisp-modes 'gerbil-mode)
+      (when (fboundp 'sp-local-pair)
+        (sp-local-pair 'gerbil-mode "'" nil :actions nil)
+        (sp-local-pair 'gerbil-mode "`" nil :actions nil)))))
 
 ;;; packages.el ends here