Fix homeassistant discover crash when device undefined.

lib/controller.js

@@ -36,7 +36,9 @@ class Controller {
         if (settings.get().homeassistant) {
             // MQTT discovery of all paired devices on startup.
             this.zigbee.getAllClients().forEach((device) => {
-                homeassistant.discover(device.ieeeAddr, deviceMapping[device.modelId].homeassistant, this.mqtt);
+                if (deviceMapping[device.modelId]) {
+                    homeassistant.discover(device.ieeeAddr, deviceMapping[device.modelId].homeassistant, this.mqtt);
+                }
             });
         }