From b8a2fafb71cd760de0fd90e3bd86c2d5faa39d3c Mon Sep 17 00:00:00 2001
From: JenChieh <jcs090218@gmail.com>
Date: Thu, 2 May 2024 15:08:40 -0700
Subject: [PATCH] feat(sideline.el): Ensure no invalid backend

---
 sideline.el | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sideline.el b/sideline.el
index 774233e..32138d2 100644
--- a/sideline.el
+++ b/sideline.el
@@ -187,6 +187,8 @@
 
 (defun sideline--enable ()
   "Enable `sideline' in current buffer."
+  (setq sideline-backends-left (cl-remove-if #'null sideline-backends-left)
+        sideline-backends-right (cl-remove-if #'null sideline-backends-right))
   ;; XXX: Still don't know why local variable doesn't work!
   (progn
     (sideline--delete-ovs)