From 5a4ca12432a011280ff4cb86e5c905380cf30abd Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 14 Jun 2019 08:40:20 +0530
Subject: [PATCH] Fix #1832780 [Error when changing
 libraries](https://bugs.launchpad.net/calibre/+bug/1832780)

---
 src/calibre/gui2/bars.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/calibre/gui2/bars.py b/src/calibre/gui2/bars.py
index c891ab29c8..7d62a358b6 100644
--- a/src/calibre/gui2/bars.py
+++ b/src/calibre/gui2/bars.py
@@ -390,7 +390,11 @@ if isosx:
                 self.clone_menu()
 
         def about_to_show(self):
+            if sip.isdeleted(self.clone):
+                return
             cm = self.clone.menu()
+            if cm is None:
+                return
             before = list(QMenu.actions(cm))
             cm.aboutToShow.emit()
             after = list(QMenu.actions(cm))