Edit book: Fix error when renaming the html file currently displayed in the preview panel and that file is not the file being currently edited

src/calibre/gui2/tweak_book/boss.py

@@ -373,6 +373,8 @@ class Boss(QObject):
             if oldname in editors:
                 editors[newname] = editors.pop(oldname)
                 self.gui.central.rename_editor(editors[newname], newname)
+            if self.gui.preview.current_name == oldname:
+                self.gui.preview.current_name = newname
         self.apply_container_update_to_gui()
     # }}}