@var? does not check existence

[238855]

I expected @car? to behave the same as car?

car? compiles to typeof car !== "undefined" && car !== null;

but

@car? compiles to this.car != null;

Should it not compile to typeof this.car !== "undefined" && this.car !== null;? It is entirely possible that somebody could reference an undefined property of @ or this

[mehcode]

Throw the following into the compiler and it might make some more sense (remember @foo is really this.foo):

foo?
this.foo?
this?.foo
this.foo?
@foo?
@?foo # errors out with "Unexpected identifier" on both original and redux

I agree that @?foo should probably compile to this?.foo which compiles to:

if (typeof this !== "undefined" && this !== null) {
  this.foo;
}

[michaelficarra]

Duplicate of many, many other issues concerning the various existential operators. See #1631.