std.json dynamic initialization of JSONValue

[Kai Meyer]

I posted this on D.learn, but got no responses. I'm hoping it's because 
I'm asking the wrong crowd.

I'm finding std.json extremely well written, with one glaring exception.

I can't seem to figure out how to do this:

JSONValue root = JSONValue(null, JSON_TYPE.OBJECT);
root.object["first_object"] = JSONValue(null, JSON_TYPE.OBJECT);
root.object["first_string"] = JSONValue("first_string", JSON_TYPE.STRING);

which would decode to:

{"first_object":{},"first_string":"first_string"}

What I end up having to do is:
JSONValue root;
root.type = JSON_TYPE.OBJECT;
root.object["first_object"] = JSONValue();
root.object["first_object"].type = JSON_TYPE.OBJECT;
root.object["first_string"] = JSON_Value();
root.object["first_string"].type = JSON_TYPE.STRING;
root.object["first_string"].str = "first_string";

That just feels like I'm doing it wrong. Is there a way to dynamically 
initialize a JSONValue struct? If I try to intialize the JSONValue 
object with anything other than simply null, or empty string, I either 
get a compile error or a segfault at run-time.

root.object["first_object"] = JSONValue(null, JSON_TYPE.OBJECT);

compile error:
Error: overlapping initialization for integer

root.object["first_string"] = JSONValue("first_string");
run-time segfault.

Any ideas?