new message type

frontend/pshared/lib/api/responses/type.dart

@@ -1,21 +1,13 @@
 
 enum MessageType {
   success,
+  processed,
   error,
   request
 }
 
 extension MessageTypeExtension on MessageType {
-  static String toJson(MessageType value) {
-    switch (value) {
-      case MessageType.success:
-        return 'success';
-      case MessageType.error:
-        return 'error';
-      case MessageType.request:
-        return 'request';
-    }
-  }
+  static String toJson(MessageType value) => value.name;
 
   static MessageType fromJson(String json) {
     switch (json) {
@@ -25,6 +17,8 @@ extension MessageTypeExtension on MessageType {
         return MessageType.error;
       case 'request':
         return MessageType.request;
+      case 'processed':
+        return MessageType.processed;
       default:
         throw ArgumentError('Unknown HTTPMType string: $json');
     }