Plugin freezes when deleting last note

Version 1.9.0 Xfce 4.16

Repro steps:

1. Add plugin to panel - default note opens
2. Ctrl+W to delete, note disappears
3. A new default note may or may not open. If it does, repeat step 2 several times.
4. After a few times, eventually new default note won't appear. Plugin is now frozen and needs to be removed and readded.