Improve error for unknown topics

NightLight.Core/Models.fs

@@ -9,7 +9,7 @@ type Event =
     | TimeChanged of DateTime
 
 type ParseZigbeeEventError =
-    | UnknownTopic
+    | UnknownTopic of string
     | InvalidJson
     | MissingTypeField
     | MissingDataField

NightLight.Core/ZigbeeEvents.fs

@@ -37,5 +37,5 @@ let parseZigbeeEvent (message: Message) =
                 | Some(JsonValue.String "off") -> Ok(ButtonPress PressedOff)
                 | Some _ -> Error InvalidActionField
                 | None -> Error MissingActionField
-        | _ -> return! Error UnknownTopic
+        | _ -> return! Error <| UnknownTopic message.Topic
     }