Async save can enter infinite loop on error

[dhardy]

Attempting to use fn rfd::AsyncFileDialog::save_file from a container can result in an infinite loop:

[2026-03-18T11:06:28Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal] Failed to save file with zenity: No such file or directory (os error 2)
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")
[2026-03-18T11:06:28Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal] Failed to save file with zenity: No such file or directory (os error 2)
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")
[2026-03-18T11:06:28Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal] Failed to save file with zenity: No such file or directory (os error 2)
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")
[2026-03-18T11:06:28Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal] Failed to save file with zenity: No such file or directory (os error 2)
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")
[2026-03-18T11:06:28Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal] Failed to save file with zenity: No such file or directory (os error 2)
[2026-03-18T11:06:28Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")

Open (pick_file) at least only fails once (acceptable, though I'd prefer the error was reported to the application: #314):

[2026-03-18T11:08:42Z ERROR rfd::backend::xdg_desktop_portal::portal::libdbus] Failed to connect to session bus: Some("org.freedesktop.DBus.Error.NotSupported"): Some("Unable to autolaunch a dbus-daemon without a $DISPLAY for X11")
[2026-03-18T11:08:42Z WARN  rfd::backend::xdg_desktop_portal] Using zenity fallback
[2026-03-18T11:08:42Z ERROR rfd::backend::xdg_desktop_portal] Failed to pick file with zenity: No such file or directory (os error 2)