[FastSpeech2] Error logging should have better formatting

[roedoejet]

As of EveryVoiceTTS/FastSpeech2_lightning#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.

[joanise]

Looking at our use of logger.error() throughout the code base, I noticed that synthesize_text_dataset.py has two errors, one if language is not found, another if speaker is not found, but then the code proceeds anyway. Is that OK, or should that not sys.exit(1) like other error instances we have?

[joanise]

I was thinking a function simply named error(msg), which could support printf style arguments (like logger.error does), defined somewhere that will eventually be part of everyvoice-core when we create it (for now, maybe everyvoice/config/logs.py?)

logs.py should define error() and logger I guess.

[joanise]

I suggest we make this a beta milestone.