Fix Byte type None causing buffer error

[54M44R]

I do not know much about the UE GVAS format, but it seems its possible for a Byte enum_type to be None while also being a valid label for a Map?

The structure is a Byte inside of a Map being used as the key_type

Minimum reproducible save file that causes this issue (has been zipped due GitHub not supporting .sav):
min_save_file.zip

I tested the .sav by doing a roundtrip and can confirm that the save file is parsed properly to and from json. Not sure if this negatively impacts any other UE saves

[trumank]

Both named bytes (enums) and raw bytes are valid. In most cases the variant can be determined from the serialized size, however bytes inside of maps are the exception. Would need external information to inform the parser on how to handle these cases.