fix #79 enum toJson serialization

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjEnum.kt

@@ -15,6 +15,8 @@
  *
  */
 
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonPrimitive
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.obj.*
 import net.sergeych.lynon.LynonDecoder
@@ -38,6 +40,10 @@ open class ObjEnumEntry(enumClass: ObjEnumClass, val name: ObjString, val ordina
         return ordinal.compareTo(scope, other.ordinal)
     }
 
+    override suspend fun toJson(scope: Scope): JsonElement {
+        return JsonPrimitive(name.value)
+    }
+
 }
 
 object EnumBase : ObjClass("Enum") {