[FastSpeech2] Error logging should have better formatting

As of https://github.com/roedoejet/FastSpeech2_lightning/pull/20, error messages were changed to print statements, but pending a longer discussion of whether to use print statements or logger.error, these should be more visible. We will have a conversation about this in the future, but for this to work, we need to implement the following:

- [ ] we need to improve the formatting so that it is obvious that what is printed is an error
- [ ] these changes need to be made across the entire EV repo so that we don’t have multiple different ways that we handle error messages
- [ ] we should have this formatting method for error messages factored out somewhere so that we can easily manipulate the format of error messages without having to do it in a bunch of different place.