Fix some warnings. (#3416)

ElementX/Sources/Screens/CallScreen/CallScreenViewModel.swift

@@ -213,14 +213,20 @@ class CallScreenViewModel: CallScreenViewModelType, CallScreenViewModelProtocol
     }
     
     private func postMessageToWidget(_ message: ElementCallWidgetMessage) async {
+        let data: Data
         do {
-            let data = try JSONEncoder().encode(message)
-            let json = String(decoding: data, as: UTF8.self)
-            
-            await postJSONToWidget(json)
+            data = try JSONEncoder().encode(message)
         } catch {
             MXLog.error("Failed encoding widget message with error: \(error)")
+            return
         }
+        
+        guard let json = String(data: data, encoding: .utf8) else {
+            MXLog.error("Invalid data for widget message")
+            return
+        }
+        
+        await postJSONToWidget(json)
     }
     
     private func postJSONToWidget(_ json: String) async {

ElementX/Sources/Screens/CreateRoom/CreateRoomViewModel.swift

@@ -93,7 +93,7 @@ class CreateRoomViewModel: CreateRoomViewModelType, CreateRoomViewModelProtocol
                 old.roomName == new.roomName && old.roomTopic == new.roomTopic && old.isRoomPrivate == new.isRoomPrivate
             }
             .sink { [weak self] bindings in
-                guard let self = self else { return }
+                guard let self else { return }
                 updateParameters(bindings: bindings)
                 actionsSubject.send(.updateDetails(createRoomParameters))
             }