Useful stability fix

[duke4e]

Hi,

I'm using your great library and it looks like that the data I'm getting from server can be incosistent, so if the server returns no data, the app crashes in "+ (nonnull instancetype)withData:(nullable NSData *)data".

I've made the simple fix for that issue and am sharing it here with you:
id object = [NSJSONSerialization JSONObjectWithData:data ? data : [NSData data] options:NSJSONReadingAllowFragments error:&error];

[bernikowich-cedoni]

@duke4e hello.
Sorry for the late response. Can you create PR please? It will be awesome.

[bernikovich]

Fixed: https://github.com/bernikowich/NSTEasyJSON/releases/tag/1.0.6