[USABILITY] Generator doesn't validate config values

[QRiary]

So, title is pretty self descriptive, but right now user can put whatever they want in pretty much any config field and it won't throw an error, but will cause troubles, super dumb example: "wordbreak_char": "hello world" is "valid" config, while its not

This issue is just a reminder to add config value validation

[QRiary]

Should also catch wrong json syntax and pretty-print it to avoid stack trace dump

[Ikcelaks]

This isn't really a bug, so I created a new tag for usability issues