`geany 1.37 (git >= ea649d80) (built on 2020-05-21 with GTK 3.22.30, GLib 2.56.4)`
On exit from Geany, the document list component of the addons plugin causes an error message: `Gtk-CRITICAL gtk_widget_destroy: assertion 'GTK_IS_WIDGET (widget)' failed`
I have narrowed it down to the `ao_doc_list_finalize` function, and found that the `priv->overflow_menu_item`, though non-null, is invalid, i.e. `GTK_IS_WIDGET` returns false, exactly as the error message claims.
Not sufficiently familiar with the code to guess where the corruption is occurring, and hoping the maintainer may be able to shed some light.
Not a major problem, as the app is exiting anyway, just annoying.