Improve WiFi settings error handling

Currently, the frontend potentially provides no WiFi settings dictionary
but still tries to update other (IP address) settings on the interface.
This leads to a stack trace since network manager is not able to fetch
the WiFi settings from the settings dictionary. Simply fill out what
we can and let NetworkManager provide an error.

Also allow to disable a network interface which has no configuration.
This avoids an error when switching to auto and back to disabled then
press save on a new wireless network interface.

supervisor/dbus/network/setting/generate.py

@@ -199,15 +199,17 @@ def get_connection_from_interface(
     elif interface.type == InterfaceType.WIRELESS:
         wireless = {
             CONF_ATTR_802_WIRELESS_ASSIGNED_MAC: Variant("s", "preserve"),
-            CONF_ATTR_802_WIRELESS_SSID: Variant(
-                "ay", interface.wifi.ssid.encode("UTF-8")
-            ),
             CONF_ATTR_802_WIRELESS_MODE: Variant("s", "infrastructure"),
             CONF_ATTR_802_WIRELESS_POWERSAVE: Variant("i", 1),
         }
+        if interface.wifi and interface.wifi.ssid:
+            wireless[CONF_ATTR_802_WIRELESS_SSID] = Variant(
+                "ay", interface.wifi.ssid.encode("UTF-8")
+            )
+
         conn[CONF_ATTR_802_WIRELESS] = wireless
 
-        if interface.wifi.auth != "open":
+        if interface.wifi and interface.wifi.auth != "open":
             wireless["security"] = Variant("s", CONF_ATTR_802_WIRELESS_SECURITY)
             wireless_security = {}
             if interface.wifi.auth == "wep":

supervisor/host/network.py

@@ -236,7 +236,10 @@ async def apply_changes(
                 ) from err
 
         # Remove config from interface
-        elif inet and inet.settings and not interface.enabled:
+        elif inet and not interface.enabled:
+            if not inet.settings:
+                # It was and is disabled, that is fine
+                return
             try:
                 await inet.settings.delete()
             except DBusError as err: