diff --git a/src/calibre/gui2/dialogs/tag_list_editor.py b/src/calibre/gui2/dialogs/tag_list_editor.py
index d0436dc238..df4e8e05d6 100644
--- a/src/calibre/gui2/dialogs/tag_list_editor.py
+++ b/src/calibre/gui2/dialogs/tag_list_editor.py
@@ -680,7 +680,5 @@ class TagListEditor(QDialog, Ui_TagListEditor):
         self.table.sortByColumn(2, Qt.SortOrder(self.was_order))
 
     def accepted(self):
-        self.links = {}
-        for r in range(0, self.table.rowCount()):
-            self.links[self.table.item(r, 0).text()] = self.table.item(r, 3).text()
+        self.links = {self.table.item(r, 0).text():self.table.item(r, 3).text() for r in range(self.table.rowCount())}
         self.save_geometry()
diff --git a/src/calibre/gui2/ui.py b/src/calibre/gui2/ui.py
index 2d6dafea63..93013cf814 100644
--- a/src/calibre/gui2/ui.py
+++ b/src/calibre/gui2/ui.py
@@ -698,6 +698,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
             library_id = decode_library_id(library_id)
             library_path = self.library_broker.path_for_library_id(library_id)
             if library_path is None:
+                prints('Ignoring unknown library id', library_id, file=sys.stderr)
                 return
             try:
                 book_id = int(book_id)