Yaml loader doesn't work with new files.

So I pulled the YAML serializer into a project today for something a bit cleaner than the default and when recording was immediately greated with:

    interactions = self.serialized.get('http_interactions', [])
AttributeError: 'NoneType' object has no attribute 'get'

What's happening here is that if the cassette doesn't exist in betamax then an empty file will be created. I'm not sure why this is better. Betamax will then read this empty file and the standard JSON decoder will fail to load the b'' content, triggering the ValueError and returning an empty dict.

Unfortunately this is not how the yaml deserializer works and trying to deserialize b'' returns None, without triggering the error and so None is returned and there is no http_interactions element.

Given this will fail basically immediately and this repo was last updated a year ago - should I just assume this is unmaintained and should not be used?