https://issues.dlang.org/show_bug.cgi?id=15331
but it's true !There's **nothing** to check the availability of a Key. At least I would expect opIndex[string key] to return a JSONValue with .type == JSON_TYPE.NULL, but no...
Also If it was returning a JSONValue* it would be easyer to check if a key is present.
God damn it, how could you miss this design flaw when std.json was reviewed ?!
