add warning for invalid code

lib/device/light.js

@@ -102,9 +102,12 @@ export default class {
           // Return now, so we don't hit the code below for removing the characteristic
           return;
         }
+
+        // If here then the scene code exists in the config but is invalid format
+        accessory.logWarn(`[${scene}] is not a valid code - please update with a new code from the log that starts with 33`);
       }
 
-      // If here then either not set up or code is invalid or connection method not enabled
+      // If here then either code is invalid or has been removed, so remove the characteristic
       if (this.service.testCharacteristic(this.cusChar[charName])) {
         this.service.removeCharacteristic(this.service.getCharacteristic(this.cusChar[charName]));
       }