Scala : Logging into system output

The application uses unstructured logging (error messages are outputted to standard out or err). Instead, it is recommended to use a structured logging, which can generate a log with the levels, time stamps, standard formatting. Using standard streams to output error messages while there is a mechanism of structured logging in a program can lead to absence of critical information in the log.

Outputting error messages to standard streams is only permissible on the early stages of development.