Fixed message for exception_failed_to_convert_to_json

Fixed indentation

library/kernel/ejson.e

@@ -245,7 +245,7 @@ feature {NONE} -- Implementation (Exceptions)
 		do
 			Result := exception_prefix + "Failed to convert JSON_VALUE to an Eiffel object: " + a_value.generator
 			if base_class /= Void then
-                Result.append (" -> " + base_class)
+				Result.append (" -> {" + base_class + "}")
 			end
 		end
 
@@ -254,7 +254,7 @@ feature {NONE} -- Implementation (Exceptions)
 		do
 			Result := exception_prefix + "Failed to convert Eiffel object to a JSON_VALUE"
 			if an_object /= Void then
-				Result := ": " + an_object.generator
+				Result.append (" : {" + an_object.generator + "}")
 			end
 		end