0d571e9191
The fallback path broke when we removed support for window icons. Nowadays we track all windows, and as a result should always have an associated app (although not necessarily backed by a .desktop file), so this shouldn't make a difference in practice. Not to mention that external docks (like cairo-dock) are extremely rare themselves now. Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3295>