Fritz: fix unbound topology (home-assistant#66877)

Co-authored-by: Michael <[email protected]>
Co-authored-by: Paulus Schoutsen <[email protected]>

homeassistant/components/fritz/common.py

@@ -331,6 +331,7 @@ def scan_devices(self, now: datetime | None = None) -> None:
         _LOGGER.debug("Checking host info for FRITZ!Box device %s", self.host)
         self._update_available, self._latest_firmware = self._update_device_info()
 
+        topology: dict = {}
         if (
             "Hosts1" not in self.connection.services
             or "X_AVM-DE_GetMeshListPath"
@@ -372,7 +373,7 @@ def scan_devices(self, now: datetime | None = None) -> None:
 
         mesh_intf = {}
         # first get all meshed devices
-        for node in topology["nodes"]:
+        for node in topology.get("nodes", []):
             if not node["is_meshed"]:
                 continue
 
@@ -389,7 +390,7 @@ def scan_devices(self, now: datetime | None = None) -> None:
                     self.mesh_role = MeshRoles(node["mesh_role"])
 
         # second get all client devices
-        for node in topology["nodes"]:
+        for node in topology.get("nodes", []):
             if node["is_meshed"]:
                 continue